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OUTLINES  OF  THE 

EVOLUTION  OF  WEIGHTS  AND  MEASURES 
AND   THE   METRIC   SYSTEM 


OUTLINES  OF 

THE  EVOLUTION  OF 

WEIGHTS  AND  MEASURES 

AND 

THE    METRIC    SYSTEM 


BY 

WILLIAM  HALLOCK,  PH.D. 

it 

PROFESSOR   OF   PHYSICS   IN   COLUMBIA   UNIVERSITY   IN  THE   CITY   OF  NKW   YORK 

AND 

HERBERT   T.  WADE 

EDITOR    FOR   PHYSICS    AND    APPLIED    SCIENCE,    '  THK   NEW    INTERNATIONAL    ENCYCLOPAEDIA 


OF  THE 

UNIVERSITY 

of 


|Uto 
THE    MACMILLAN    COMPANY 

LONDON  :    MACMILLAN   AND   CO.    LTD. 
1906 


GLASGOW  :    PRINTED   AT   THE   UNIVERSITY    PRESS 
BY  ROBERT  MACtEHOSE  AND  CO,    LTP. 


PREFACE. 

IN  the  following  pages  it  has  been  the  aim  of  the  authors  to 
present  in  simple  and  non-technical  language,  so  far  as  possible,  a 
comprehensive  view  of  the  evolution  of  the  science  of  metrology 
as  it  is  now  understood.  Inasmuch  as  the  introduction  of  the 
Metric  System  into  the  United  States  and  Great  Britain  is  a 
topic  of  more  or  less  general  interest  at  the  present  time,  it  has 
seemed  that  a  work  designed  both  for  the  student  of  science  and 
for  the  general  reader,  in  which  this  system  is  discussed  in  its 
relation  to  other  systems  of  weights  and  measures  past  and 
present,  would  fill  a  certain  need.  While  there  are  many  works 
on  metrology  that  treat  at  considerable  length  the  historic  and 
scientific  sides  of  the  subject,  as  well  as  the  economic  and 
archaeological  questions  involved,  and  a  large  number  of  books 
and  pamphlets  dealing  with  the  teaching  of  the  Metric  System, 
besides  those  supplying  tables  and  formulas  for  converting  from 
one  system  to  the  other,  yet  there  is  apparently  a  distinct  lack  of 
works,  which  in  small  compass  discuss  the  subject  comprehensively 
from  its  many  points  of  view.  Indeed,  the  student  of  metrology 
is  apt  to  be  embarrassed  by  an  extensive  literature  rather  than 
by  any  deficiency  in  the  amount  of  collected  material,  though 
much  of  the  latter,  to  be  sure,  is  included  in  various  Reports  and 
Proceedings  of  learned  societies  and  official  documents  rather  than 
in  single  works.  A  large  amount  of  this  literature  devoted  to 
metrology  represents  a  minute  specialization  and  critical  analysis 
often  discussing  either  a  certain  epoch,  or  a  single  system  or 
group  of  weights  and  measures,  where  the  treatment  is  from  the 
standpoint  of  either  archaeology,  economics,  or  physical  or  mathe- 
matical science,  and  but  rarely  combining  the  three  points  of 


176295 


vi  PREFACE 

view.  In  addition,  much  of  this  literature  is  of  an  argumentative 
nature,  and  debate  and  discussion  rather  than  definite  conclusions 
compelling  universal  acceptance  seem  to  be  characteristic  of 
metroTogical  writing. 

It  has  been  the  intention  of  the  authors  to  consider  briefly  and 
systematically  the  general  history  of  weights  and  measures,  the 
scientific  methods  by  which  units  and  standards  have  been 
determined,  the  concrete  standards  by  which  the  units  are 
represented,  and  the  present  aspect  of  modern  systems  of  weights 
and  measures,  together  with  the  difficulties  and  advantages 
involved  in  any  proposed  changes.  Experience  derived  while 
giving  instruction  in  physics  to  students  in  applied  science  has 
suggested  the  general  plan  of  treatment,  and  it  has  seemed 
desirable  to  present  from  an  American  standpoint  the  most 
essential  facts  in  as  logical  relation  as  is  possible  in  a  science 
that  is  often  marked  by  conditions  quite  illogical.  From  the 
copious  notes  and  bibliographical  references,  which  it  is  hoped  will 
be  appreciated  by  advanced  students  and  those  specially  interested 
in  the  subject,  it  will  be  seen  that  at  the  outset  any  claims  to 
striking  originality  must  be  dismissed,  and  the  obligations  of  the 
authors  to  the  various  authorities  mentioned  in  the  notes  are 
ungrudgingly  acknowledged. 

The  authors  hope  that  their  work  will  serve  two  useful  ends : 
first,  as  an  introduction  to  metrological  science  designed  especially 
for  the  student  entering  on  the  study  of  physics  to  whom  a 
knowledge  of  units  and  standards  is  most  necessary ;  and  second, 
as  preparatory  to  an  intelligent  understanding  of  the  discussions 
involved  in  the  proposed  adoption  of  the  Metric  System  by 
English-speaking  peoples,  especially  by  those  to  whom  Metric 
and  Anti-Metric  arguments  are  being  addressed  with  such 
frequency  and  persistence.  It  has  been  the  intention  of  the 
authors  to  avoid  as  far  as  possible  all  controversy  for  several 
reasons ;  the  first  and  most  important  of  which  is  that  this  side 
of  the  question  has  been  and  is  being  abundantly  covered 
elsewhere,  so  that  it  has  seemed  preferable  in  this  work  to 
include  a  mere  statement  of  facts  rather  than  to  repeat  or  even 
add  to  the  arguments.  Such  has  been  their  intention,  but  they 
are  also  compelled  to  admit  that  they  are  supporters  of  the 
Metric  propaganda,  and  they  must  ask  indulgence  for  any 


PREFACE  vii 

departures  from  the  plan  determined  on.  However  that  may 
be,  they  have  endeavored  to  give  a  fair  and  concise  history  of 
the  Metric  System  so  that  its  logical  development  and  character- 
istics will  be  apparent,  and  this,  together  with  the  experience  of 
European  nations  as  briefly  described,  will  supply  sufficient  data 
on  which  may  be  formed  an  intelligent  opinion  as  to  the 
desirability  of  adopting  in  America  and  Great  Britain  at  an 
early  date  the  International  System  of  weights  and  measures. 

In  view  of  the  fact  that  such  a  work  has  involved  the  use  of  a 
vast  number  of  authorities,  it  is  manifestly  impossible  to  specify 
in  detail  other  than  in  the  notes  the  great  indebtedness  on  the 
part  of  the  authors  to  the  labors  of  many  famous  metrologists. 
Naturally  they  have  consulted  freely  the  classic  work  of  Mechain 
and  Delambre,  Base  du  systeme  Metrique ;  General  Morin's 
Notice  Jiistorique  sur  le  systeme  Metrique ;  Bigourdan's  Le  systeme 
Mttrique ;  Guillaume's  La  Convention  du  Metre ;  and  his  excellent 
little  treatise  on  Unite's  et  Etalons,  as  well  as  Benoit's  Report  on 
Standards  of  Length  to  the  International  Physical  Congress  of 
1903.  In  addition  they  have  used  the  various  publications  of  the 
International  Bureau  of  Weights  and  Measures.  For  ancient 
weights  and  measures  many  sources  have  been  consulted,  while 
for  English  standards  and  metrology  the  works  of  Chisholm  and 
Chaney  have  been  found  most  helpful,  but  they  have  been 
supplemented  by  various  papers  of  Parliamentary  commissions 
and  the  Proceedings  of  scientific  societies.  In  the  United  States 
the  Reports  and  other  papers  of  the  Coast  and  Geodetic  Survey, 
the  recently  established  National  Bureau  of  Standards,  and  the 
Committees  on  Coinage,  Weights  and  Measures,  of  the  House  of 
Representatives  have  formed  a  nucleus  that  has  been  supple- 
mented by  extensive  reference  to  other  scientific  literature. 

In  conclusion  the  authors  would  gratefully  acknowledge  their 
obligations  to  M.  Ch.  Ed.  Guillaume,  Assistant  Director  of  the 
International  Bureau  of  Weights  and  Measures,  and  Professor 
S.  W.  Stratton,  Director  of  the  U.S.  Bureau  of  Standards,  who 
most  kindly  consented  to  look  over  the  proofs  and  have 
rendered  assistance  in  many  substantial  ways. 


CONTENTS. 
CHAPTER   I. 

PAGE 

BEGINNINGS  AND  DEVELOPMENT  OF  THE  SCIENCE  OF  METROLOGY,      1 

Underlying  Principles  of  Metrology.  Development  of  the  Science 
among  Primitive  Peoples.  Metrology  of  the  Babylonians.  Hebrew 
Metrology.  Weights  and  Measures  among  the  Egyptians.  Greek 
Weights  and  Measures.  The  Roman  System  and  its  Spread. 
Mediaeval  Conditions.  Development  of  Anglo-Saxon  Metrology. 
Early  French  Weights  and  Measures.  European  Conditions 
Generally. 

CHAPTER   II. 

ORIGIN  AND  DEVELOPMENT  OF  THE  METRIC  SYSTEM,  41 

Reasons  for  the  Change  and  Preliminary  Efforts.  Scientific  and 
Other  Steps  in  its  Development.  The  Derivation  of  the  Meter 
and  Kilogram.  Adoption  of  the  System.  Method  of  bringing 
about  the  Change.  Systeme  Usuelle.  Spread  of  the  Metric 
System  and  Compulsory  Legislation  of  1837.  The  Metric  Treaty 
and  the  Formation  of  the  International  Bureau  of  Weights  and 
Measures.  Work  and  Organization  of  the  Bureau. 

CHAPTER   III. 

EXTENSION  OF  THE  METRIC  SYSTEM  THROUGHOUT  EUROPE  AND 

ELSEWHERE,  80 

Confusion  Existing  and  Reasons  for  the  Change.  Dates  and 
Methods  of  Making  the  Change — Germany.  Austria.  Hungary. 
Belgium.  Egypt.  Greece.  Italy.  Japan.  Netherlands.  Portugal. 
Russia.  Spain.  Sweden  and  Norway.  Switzerland.  Turkey. 
Great  Britain.  Mexico.  South  and  Central  America.  Table 
showing  Dates  when  Metric  System  was  adopted. 


x  CONTENTS 

CHAPTER   IV. 

PAGE 

WEIGHTS  AND  MEASURES  IN  THE  UNITED  STATES,  -  -    109 

Connection  of  Weights  and  Measures  with  Systems  of  Currency. 
Development  of  the  Decimal  Principle.  Early  National  Legisla- 
tion. Various  Plans  Proposed.  John  Quincy  Adams'  Report  on 
Weights  and  Measures.  The  Development  of  a  National  System 
and  Progress  towards  Uniformity.  Early  Standards  and  Definitions. 
Spread  of  the  Metric  System.  Summary  of  Metric  Legislation. 


CHAPTER   V. 

THE  METRIC  SYSTEM  OP  TO-DAY — ITS  ESSENTIAL  CHARACTER- 
ISTICS AND  FUNDAMENTAL  PRINCIPLES,       -  -     135 

General  Characteristics.     Linear  Measures.     Superficial  Measures. 
Cubical  Measures.     Measures  of  Capacity.     Measures  of  Mass. 


CHAPTER   VI. 

THE  METRIC  SYSTEM  FOR  COMMERCE,  -    150 

The  Advantages  of  a  Universal  System.  The  Metric  System  for 
International  Trade.  Its  Applicability  to  the  Ordinary  Transaction 
of  Commerce.  The  Advantages  of  a  Homogeneous  and  Decimal 
System. 

CHAPTER  VII. 

THE  METRIC  SYSTEM  IN  MANUFACTURING  AND  ENGINEERING,     172 

Simplicity  of  Metric  System.  Ease  with  which  Change  could  be 
made.  Question  of  Gauges.  Linear  Measurements  in  Mechanical 
Engineering.  The  Question  of  Screw  Threads.  Introducing  the 
Metric  System  into  a  Machine  Shop. 

CHAPTER   VIII. 
THE  METRIC  SYSTEM  IN  MEDICINE  AND  PHARMACY,  191 

General  Nature  of  its  Use  and  its  Advantages.  Adoption  by 
U.S.  Army  and  Navy  Medical  Departments. 


CONTENTS  xi 

CHAPTER   IX. 

PAQB 

INTERNATIONAL  ELECTRICAL  UNITS,  -    199 

The  Absolute  System.  Derivation  of  Electrical  Units  from  the 
Metric  'System.  The  C.G.S.  System  of  the  British  Association. 
Definitions  of  Electrical  Units  at  Chicago,  1893.  Specifications 
for  the  Practical  Application  of  these  Definitions.  New  Magnetic 
Units.  Shortcomings  of  Present  Units. 

CHAPTER   X. 

STANDARDS  AND  COMPARISON,  -  218 

Nature  and  History  of  Standards.  Methods  of  Comparison. 
Present  Day  Standards.  Definition  of  the  Meter  in  terms  of  the 
Wave  Length  of  Light. 

APPENDIX. 

TABLES  OF  EQUIVALENTS  AND  USEFUL  CONSTANTS,  267 

U.S.  Legal  Equivalents.  British  Legal  Equivalents.  Table  for 
Conversion  of  Units  of  Length.  Table  for  Conversion  of  Units 
of  Mass.  Equivalents,  Millimeters  and  Fractions  of  an  Inch. 
Comparison  of  Prices  :  Length — Inches  and  Centimeters,  Feet  and 
Meters,  Yards  and  Meters,  Miles  and  Kilometers.  Areas — Acres 
and  Hectares.  Capacity — Liquid  Quarts  and  Liters,  Gallons  and 
Liters.  Mass — Avoirdupois  Pounds  to  Kilograms,  Comparison  of 
Tons  and  Pounds.  Capacity — Various  Equivalents.  Mass — Various 
Equivalents.  Apothecaries'  Weight — Table  of  Equivalents.  Den- 
sity, Melting  Point  and  Boiling  Point  Tables.  Thermometer  Scales 
— Table  of  Equivalents.  Miscellaneous  Constants  and  Equivalents. 

INDEX,  -    295 


CHAPTEK  I. 

OKIGIN  AND  DEVELOPMENT  OF  THE   SCIENCE  OF 
METROLOGY. 

FEW  questions  concern  the  human  race  more  directly  and 
universally  than  the  subject  of  weights  and  measures.  In  fact, 
so  intimate  is  this  connection  that  the  common  weights  and 
measures  of  a  people  bear  much  the.  _same  relation  to  it  as  does 
the  language— oi;_  ordinary^speech,  being  assumed  and  applied  in 
their  daily  occupations  without  active  thought,  and  resisting 
changes  and  reforms,  even  when  brought  about  by  the  most 
strenuous  efforts  and  with  convincing  proof  of  their  desirability 
or  necessity.  [For  the  origin  of  weights  and  measures  it  is 
necessary  to  go  back  to  the  earliest  days  of  the  human  race  and 
deal  with  the  elementary  mental  processes  of  primitive  man.  The 
idea  of  measuring  must  have  been  closely  akin  to  that  of 
number,  which,  of  course,  implied  the  perception  that  certain 
objects  could  be  grouped  together  either  actually  or  at  least 
ideally.  The  next  step  would  be  the  comparison  of  the  various 
objects  of  such  a  group,  and  this  would  involve  a  simple  ratio 
in  terms  of  one  of  the  members  of  the  group.  When  the 
comparison  was  extended  to  other  groups,  there  was  need  of  a 
standard,  and,  when  various  classes  of  objects  were  compared, 
a  standard  had  to  be  selected  which  would  answer  in  common. 
Such  standards  would  readily  suggest  themselves.  If  it  took  a 
certairTlilmiLer  of  days  and  nights  to  make  a  journey,  the  distance 
travelled  in  one  day,  that  is  from  one  sunrise  or  sunset  to 
the  next,  would  straightway  be  considered  as  a  natural  measure 
of  journeys  of  considerable  duration,  while,  for  shorter  distances, 


2         EVOLUTION   OF   WEIGHTS   AND   MEASURES 

r  the  pace  as   a    regularly   recurring    interval   would   be  adopted 
7for   measuring  the    total   distance,   and   the    single   pace   would 
be  taken  as  a  unit. 

For  measuring  still  smaller  distances  the  primitive  man  would 
.take,  say  the  length  of  his  foot  or  the  breadth  of  his  hand,  as  it 
would  be  most  convenient  for  him  to  employ  as  units  in  his 
measurements  the  objects  usually  at  hand,  and  it  was  but 
natural  that  the  dimensions  of  the  body  would  furnish  such 
units.  Thus  for  linear  measures  there  would  be  employed  the 
breadth  of  the  first  joint  of  the  forefinger,  the  breadth  of  the 
hand,  the  span  of  the  extended  fingers  of  one  hand,  the  length  of 
the  foot,  the  length  of  the  forearm,  the  step  or  single  pace,  the 
double  pace,  and  the  distance  between  the  tips  of  the  fingers 
when  the  arms  were  outstretched.  All  of  these  distances  figured 
in  the  early  systems  of  linear  measures  of  the  ancients,  and,  in 
fact,  great  diversity  of  measures  was  a  characteristic  of  early 
civilization,  due  to  the  fact  that  originally  only  the  convenience 
of  the  individual  had  to  be  consulted.  With  the  growth  of 
society  the  tendency  was  toward  uniformity,  and  this  tendency, 
with  but  occasional  retrogressions,  has  been  maintained.  When 
several  persons  were  concerned  in  the  comparison  of  the  size  of 
an  object  or  some  other  kind  of  measurement,  it  was  necessary 
to  consult  the  convenience  of  the  group  rather  than  that  of  the 
individual,  while  with  the  development  of  trade  there  was 
also  added  the  idea  of  equity. 

Along  with  the  general  tendency  of  progress  from  diversity 
to  uniformity  of  measures  in  the  evolution  of  society,  must  also 
be  considered  the  securing  of  uniformity  of  single  measures. 
Thus,  if  a  pace  or  length  of  a  forearm  was  a  convenient  unit  for 
a  number  of  individuals,  it  would  soon  become  necessary  to 
specify  the  class  of  individuals,  or,  better  still,  the  single  indi- 
vidual whose  pace  or  forearm  was  to  be  the  standard;  was  it  to 
be  that  of  a  man  six  feet  in  height  or  one  considerably  shorter  ? 
Such  a  discussion  could  not  but  lead  to  the  actual  measuring 
of  the  pace  or  forearm  which  would  by  common  consent  serve  as 
the  measure,  and  then  by  laying  off  the  distance  on  some  surface 
a  standard  or  concrete  reproduction  of  the  unit  would  be  con- 
structed which  would  answer  for  the  family  or  small  group. 
Just  as  it  was  necessary  for  the  family  to  come  to  some 


THE   SCIENCE   OF   METROLOGY  3 

understanding  as  to  what  measures  would  be  standard  for  their 
household,    so    it   was   soon    realized   that   the    interests  of    all 
would  best  be  subserved  if  a  single  system  should  be  employed 
throughout  the  tribe,  either  by  a  gradual  adoption  of  a  common 
mean,  or  by  having  some  standard  imposed  by  authority  emana- 
ting from  the  ruler  or  headmen  of  the  tribe.     This  latter  practice 
was  the  more  prevalent,  and,  remarkable  to   say,  has  persisted 
to  modern  times.     So  late  as  the  time  of  Henry  I.  the  length  of 
the  English  yard,  according  to  tradition,  was  fixed  by  the  length 
of  the  sovereign's  arm,  while  even  in  the  United  States  in  nearly  - 
all  cases  the  national  standards  of  weights  and  measures  have  ' 
been  determined  by  executive  order  rather  than  by  legislative  ' 
action. 

While  the  foregoing  observations  would  also  hold  true  in  the 
case   of  weights,   yet   in    connection  with  the    latter  there   are 
certain  additional  matters  to  be  considered.     When  the  primitive 
man  had  advanced   in   civilization  to  a  point  where  he  looked 
beyond  his  immediate  needs,  he  would  doubtless  own  a  certain 
number  of  slaves  and  domestic  cattle,  and  his  life  being  spent  in  - 
>  an   habitation   or    home   more   or   less  permanent,  it   would  be  •" 
natural    for    him    to     accumulate     stores     of    grain    and    other 
substances  both  for  his    future  wants  and  to  barter  for    other 
commodities.     Now,  it   seems  that  the   earliest  unit  of   wealth   » 
and  basis  of  exchange  was  the  ox  or  cow,  and  this  soon  found 
an  equivalent  in  a  certain  amount  of  gold,  a  substance  which, 
on    account    of    its    practically    universal    distribution    and    its 
uniform  scarcity,  could  readily  be  given  a  fixed  value  in  terms 
of   cows    or    oxen.1     This    would    involve    some    rude    form    of 
measurement,  such  as  a  goose-quill  for  the  measurement  of  gold 
dust  by  capacity,  or  a  linear  measurement  if  the  gold  was  in  the 
form  of  wire  or   strips,   and  eventually  the  use  of  a  primitive 
balance  with   the   natural   seeds   of   plants  for  weights.     These   * 
seeds_indisputably  were  the  first  weights,  as  can  be  proved  by 
studying  the  habits  of  primitive  peoples  past  and  present,  where 
such  use  of  seeds  has  been  and  is  practically  universal,  and  this 
custom,  furthermore,  has   survived  in  the  grains  of  the  Anglo- 
Saxon  weights  and  the  carat  (from  the  Arab  carob  or  bean)  of  i 
the   dealers   in   precious  stones.     But   this   early   weighing   was 

iRidgeway,  Origin  of  Metallic  Money  and  Weights  (Cambridge,  Eng.,  1892). 


4         EVOLUTION   OF   WEIGHTS   AND   MEASURES 

confined  to  gold  for  purposes  of  trade,  and  to  other  metals,  such 
as  silver  and  copper,  when  they  were  subsequently  used  for 
a  similar  purpose;  and  this  is  amply  demonstrated  by  early 
Egyptian  records  where  mention  is  made  of  weighing  only  gold, 
silver,  and  copper,  and  lapis  lazuli,  until  the  time  of  the  seven- 
teenth dynasty.  As  it  was  not  until  the  seventh  century  B.C. 
that  coined  money  was  used,  this  weighing  of  metals  was 
universal,  and  the  use  of  the  balance  was  required  in  practically 
all  transactions,  as  when  "  Abraham  weighed  to  Ephron  the 
silver  which  he  had  named  in  the  audience  of  the  sons  of 
Heth,  four  hundred  shekels  of  silver,  current  money  with  the 
merchant "  (Gen.  xxiii.  16). 

It  followed  naturally  from  such  universal  weighing  that 
.certain  units  should  be  formed,  made  up  of  a  certain  number  of 
seeds  and  reproduced  by  stone  or  metal  standards.  Though  we 
may  agree  with  Ridgeway  that  the  earliest  weighings  were 
empirical,  and  were  carried  on  by  seeds  and  natural  standards 
"  before  ever  the  sages  of  Thebes  or  Chaldaea  had  dreamed  of 
applying  to  metrology  the  results  of  their  first  gropings  in 
Geometry  or  Astronomy,"  x  yet  we  must  admit  that  some  sort  of 
a  mathematical  system  of  units  of  weight  was  bound  to  come 
where  weighing  was  so  widespread.  Then  with  the  development 
of  civilization,  especially  as  regards  science  and  commerce,  it  was 
but  natural  that  these  weights  should  be  defined  either  by  royal 
decree  or  by  common  consent,  and  be  based  upon  a  standard 
which,  according  to  some  metrologists,  was  scientifically  deter-*' 
mined,  or  in  the  opinion  of  others  was  merely  an  arbitrary 
weight  or  weights.  At  all  events  it  must  be  borne  in  mind  in 
considering  questions  of  metrology  from  the  earliest  times  down 
to  within  the  last  two  centuries  that  accuracy  in  weights  and 
measures  was  neither  demanded  nor  possible,  and  that  attempts 
of  archaeologists  accurately  to  weigh  the  weights  or  measure  the 
linear  scales  from  old  ruins,  and  to  use  small  differences  in 
forming  their  theories,  are  in  most  cases  quite  unwarranted. 
There  is,  however,  indisputably  a  certain  amount  of  corre- 
spondence among  the  weights  and  measures  of  antiquity  due  to 
commercial  intercourse  which  took  place  both  by  sea  and  by 
caravan,  and  which  was  much  greater  than  we  would  b.e  apt  to 

1  Ridgeway,  p.  232. 


THE   SCIENCE   OF   METROLOGY  5 

suspect,   and   this   should   of    course   receive  due  weight   in  all 
discussions  of  the  metrology  of  the  ancients. 

For  the  measure  of  capacity  it  is  quite  obvious  that  the 
earliest  units  were  natural  objects  such  as  eggs  or  gourds,  and  that  a 
basket  or  jar  would  be  constructed  by  a  certain  tribe  which  would 
be  of  a  convenient  capacity  for  the  purposes  for  which  it  was 
used,  such  as  carrying  grain  or  water.  Such  natural  or  arbitrary 
units  would  straightway  find  application  and  would  doubtless  fill 
all  needs,  as  capacity  measurements  would  be  of  the  simplest 
nature  possible.  In  fact,  with  certain  primitive  peoples,  as  is 
now  the  case  among  some  Asiatic  tribes,  units  of  measure  of 
capacity  were  quite  unknown,  and  it  is  the  general  tendency  for.' 
units  of  capacity  to  come  after  units  of  weight.  If  we  are  to 
follow  the  theories  of  some  metrologists  we  must  assume  that  the 
ancients  derived  their  units  of  capacity  from  a  cube  one  of  whose 
sides  was  the  linear  unit,  and  that  the  unit  of  weight  was  this, 
or  a  proportionate  cube,  which  was  filled  with  pure  water.  In 
fact,  such  a  process  would  give  a  unit  of  area  by  taking  a  square 
whose,  side  was  a  linear  unit,  and  a  cubical  measure  formed  by  a 
unit  cube  whose  edge  was  a  linear  unit.  Whether  or  not  the 
ancients  followed  such  a  process  of  reasoning  it  is  impossible  to 
say,  but  on  both  sides  of  the  question  there  are  many  arguments 
which  will  briefly  be  referred  to  a  few  pages  further  on. 

While  the  development  of  weights  and  measures  is  a  gradual 
evolution,  yet  it  is  a  complex  matter  to  which  so  many  influences 
have  contributed  that  it  is  difficult  to  trace  any  clear  course  or 
logical  development.     Ethnic  conditions,  the  whims  and  caprices  \ 
of  rulers,  imposition  and  fraud,  conquest,  and  methods  and  habits  \ 
of  thought  and  life,  all  in  turn  have  had  their  effect.     Never- 
theless the  growth  of  scientific  knowledge  and  its  application,  the 
influence   of    the   market-place,  as    well   as    that   of    a   broader 
commerce  and  laws  and  customs,  in  every  nation  have  tended  to  / 
bring  together  into  something  more  or  less  resembling  a  system  I 
all  matters  connected  with  weighing  and  measuring  built  up  on  I 
such  units  as  the  tribe  or  nation  had  selected  for  their  inter-J 
change  of  commodities  and  ideas. 

For  the  units  or  bases  of  such  systems  it  is  possible  to  select 
two  different  classes  of  quantities,  arbitrary  and  natural,  and  to?* 
use   them   in  their   development.      By  an    arbitrary  quantity  is 


6         EVOLUTION   OF   WEIGHTS   AND   MEASURES 

meant  one  that  is  selected  without  reference  to  its  occurrence  in 
any  natural  object  or  condition,  but  merely  a  certain  distance, 
mass,  etc.,  which  will  furnish  a  convenient  basis  both  in  its 
original  state  and  by  its  multiples  and  submultiples,  for  the 
measurements  to  which  it  will  be  applied.  In  actual  practice 
the  result  has  been,  in  spite  of  many  attempts  to  construct 
systems  based  on  natural  units,  that  the  fundamental  units  are 
arbitrary,  and  where  interrelated  are  based  upon  actual  standards 
of  length  rather  than  distances  found  in  nature.  As  examples  of 
natural  units  might  be  cited  the  measures  derived  from  the 
human  body  already  mentioned,  which  readily  connect  themselves 
one  with  another  by  certain  relations.  Thus : 

The  Digit,     -                                                     equals   1  part 
Palm  or  handbreadth,  „  4  „ 
Span,     -  „  12  „ 
Foot,      -  „  16  „ 
Cubit,    -  „  24  „ 
Step  or  single  pace,  -  „  40  „ 
Double  pace,   -  „  80  „ 
Fathom,  or  distance  between  ex- 
tended arms,    -  „  96  „ 

This  ratio  we  find  observed  in  early  systems  of  measurement,  and 
it  must  be  borne  in  mind  in  considering  them. 

As  typical  of  early  natural  measures  as  found  in  the  Orient, 
the  following  passage  from  the  writings  of  Hiuen  Tsiang  (Yuan 
Chwang),  603-668  A.D.,  a  Chinese  traveller  and  author,  of  Ho-ran, 
written  in  A.D.  629  in  regard  to  the  measures  of  India,  may  be 
cited : l 

"  In  point  of  measurements,  there  is  first  of  all  the  yojana 
(yu-shen-na) ;  this  from  the  time  of  the  holy  kings  of  old  has 
been  regarded  as  a  day's  march  for  an  army.  The  old  accounts 
say  it  is  equal  to  40  li ;  according  to  the  common  reckoning  in 
India  it  is  30  li,  but  in  the  sacred  book  (of  Buddha)  the  yojana 
is  only  16  li.  In  the  subdivision  of  distances  a  yojana  is  equal 
to  eight  kros'as  (keu-lu-she) :  a  kros'a  is  divided  into  500~  bows 
(dhanus) :  a  bow  is  divided  into  four  cubits  (hastas) :  a  cubit  is 
divided  into  24  fingers  (angulis):  a  finger  is  divided  into  7  barley- 

1Beal,  Buddhist  Records  of  the  Western  World  (London,  1884),  vol.  i.  p.  70. 


THE   SCIENCE   OF   METROLOGY  7 

corns  (yavas) :  and  so  on  to  a  louse  (yuka),  a  hit  (liksha),  a  dust 
grain,  a  cow's  hair,  a  sheep's  hair,  a  hare's  down,  a  copper  water,1 
and  so  on  for  seven  divisions,  till  we  come  to  a  small  grain  of 
dust:  this  is  divided  sevenfold  till  we  come  to  an  excessively 
small  grain  of  dust  (anu) :  this  cannot  be  divided  further  without 
arriving  at  nothingness,  and  so  it  is  called  the  infinitely  small 
(paramanu)." 

Leaving  out  of  consideration  the  source  or  antiquity  of  these 
particular  measures,  they  may  be  considered  as  exemplifying  the 
use  of  natural  circumstances  or  objects  as  units  and  their  connec- 
tion into  a  system.  However,  as  is  mentioned  in  the  case  of  the 
yqjana,  and  the  same  may  be  found  in  numerous  other  instances 
in  early  measures  not  only  in  the  Orient  but  throughout  the 
civilized  world,  the  ancient  systems  may  have  contained  units 
varying  in  value  and  in  their  relation  to  other  units.  It  may  be 
said  in  passing  that  it  is  fair  to  assume  that  these  particular 
measures  were  much  older  than  would  at  first  glance  appear  from 
the  date  of  the  work  quoted,  as  India  and  the  adjoining  countries 
boasted  a  civilization  that  was  nothing  if  not  conservative,  and 
traced  its  traditions  to  a  remote  past. 

Another  example  of  a  natural  unit,  according  to  some  of  the 
older  authorities  on  metrology,  including  Paucton,2  though  the 
theory  is  now  regarded  as  entirely  erroneous,  was  the  base  of  the 
•Great  Pyramid,  which  was  constructed  equal  to  the  five  hundredth 
part  of  a  "  degree,"  and  was  divided  into  600  Ptolemaic  feet  or 
400  Ptolemaic  cubits.  Likewise  in  the  determination  of  the  meter 
an  attempt  was  made  to  measure  the  ten-millionth-  part  of  a 
quadrant  of  a  great  circle  of  the  earth,  but  it  was  subsequently 
found  that  the  meter  thus  obtained  did  not  represent  this  fraction 
with  sufficient  accuracy,  and  it  was  concluded  to  retain  such  a  meter 
as  an  arbitrary  standard  and  as  the  basis  of  the  metric  system 
rather  than  attempt  to  secure  a  new  natural  unit  which  might 
require  subsequent  changing  with  future  scientific  developments. 

Even  after  the  metric  system  had  been  developed,  Sir  John 
Herschel,  the  British  astronomer,  proposed  as  a  standard  the 

1  Possibly  the  size  of  the  small  hole  in  the  tamri  or  copper  cup  for  the  admis- 
sion of  water. 

2  Paucton,  M&rologie,  ou  Traite  des  Mesures,  Poids  et  Monnoies  (Paris,  1780), 
chap.  i.  p.  109  et  seq. 


8         EVOLUTION   OF   WEIGHTS   AND   MEASURES 

length  of  the  polar  axis  of  the  earth,  as  500  0^0  000  Par^  °^ 
this  quantity  would  give  the  present  British  inch  very  closely.1 

Another  class  of  natural  units  that  were  employed  as  the  basis 
of  systems  of  weights  and  measures  consisted  of  the  dimensions  or 
weight  of  grains  of  barley  or  corn,  a  number  of  such  grains  being 
placed  in  a  row  to  form  such  a  unit  as  the  English  inch,  or  col- 
lected to  a  certain  number  to  form  by  their  weight  an  English 
pound. 

Whether  the  units  be  natural  or  arbitrary  there  must  be  some 
that  are  fundamental,  and  on  them  can  be  based  and  developed 
others  as  civilization,  commerce,  and  science  need  additional  units 
to  express  the  magnitudes  with  which  they  are  forced  to  deal. 
For  example,  in  the  eighteenth  century  it  was  not  possible  ^to 
make  any  measurements  of  electricity,  nor  indeed  were  such 
demanded,  yet  one  hundred  years  later  a  complete  system  of 
electrical  measurements  was  developed  based  on  measures  and 
units  previously  used.2 

For  fundamental  units  it  is  possible  and  most  convenient  to 
start  with  the  unit  of  length  and  develop  from  it  units  of  weight 
and  capacity  by  taking  a  volume  equal  to  that  of  a  cube,  each 
side  of  which  is  equal  to  the  selected  unit  of  length,  and  then 
filling  it  with  water,  as  was  done  with  the  modern  metric  system, 
and  is  a  feature  claimed  for  the  weights  and  measures  of  the 
ancient  Babylonians.  Similarly,  units  of  area  could  be  developed 
by  taking  a  square  whose  side  is  the  linear  unit,  and  with  the 
addition  of  a  unit  of  time,  units  of  velocity,  acceleration,  etc., 
could  readily  be  derived.  By  the  time  that  these  and  other 
required  units  were  obtained,  they  naturally  would  become  asso- 
ciated into  a  system  of  more  or  less  logical  relation  and  arrange- 
ment. In  such  a  system  there  necessarily  would  be  a  number  of 
different  units  for  different  classes  of  quantities,  and  these  would 
be  multiples  and  sub-multiples  of  each  other.  Such  arrangements 
and  systems  would  reflect  the  methods  of  thought  of  the  people 
by  whom  they  were  developed.  Accordingly  in  ancient  Egypt 
and  also  in  China  we  find  a  de£imaL_system  employed  as  in  their 
system  of  numerical  notation,  while  among  the  Babylonians, 
Chaldaeans,  Assyrians,  and  the  Egyptians  of  certain  later  dynasties 

1See  chapter  vi.,  p.  164. 

2 See  chapter  ix.— Electrical  Units. 


THE   SCIENCE   OF   METROLOGY  9 

the  basis  of  division  was  sexagesimal,  as  is  retained  in  our  modern  - 
notation  of  time.  The  Eomans  used  the  duodecimal  system, 
where  the  foot,  sextarius  (measure  of  capacity),  libra  (pound),  etc.,, 
were  divided  into  twelve  equal  parts.  With  the  Hindus  there  • 
was  the  binary  subdivision  which  was  also  followed  by  the  Ger- 
manic and  Teutonic  peoples,  and  also  by  the  Arabs,  despite  their 
decimal  system  of  notation.  These  examples  show  how  national 
or  racial  conditions  affect  the  development  of  a  system  of  weights 
and  measures,  and  of  course  as  the  political,  commercial,  or  intel- 
lectual influence  of  a  nation  extended  it  was  but  natural  that 
with  it  would  go  its  weights  and  measures,  which,  if  not  sup- 
planting those  of  other  countries,  at  least  in  many  cases  would 
have  a  corrupting  and  disintegrating  influence. 

In  any  attempt  at  a  brief  historical  survey  of  the  origin  and 
history  of  weights  and  measures  there  are  many  matters  to  be  taken 
into  consideration  which  prevent  a  complete  and  comprehensive 
sketch  of  the  subject.  For  over  two  centuries  there  has  been  much 
attention  devoted  to  ancient  metrology,  and  many  and  contra- 
dictory theories  have  been  advanced.  They  are  for  the  most 
part  founded  on  data  or  hypotheses  by  no  means  satisfactory ; 
though  in  nearly  all  instances  plausible  cases  which  often  show 
the  greatest  study  and  ingenuity  have  been  made  out  by  workers 
whose  sincerity  and  industry  cannot  be  questioned.  In  certain 
of  these  systems  and  theories  the  ancients  are  credited  with  a 
knowledge  of  mathematics,  both  theoretical  and  applied,  which 
some  scholars  do  not  think  at  all  warranted,  while  other  systems 
have  been  built  up  on  limited  data,  often  text  allusions  in  ancient 
literature  and  inscriptions,  which  though  harmonious  to  a  greater 
or  less  extent  do  not  absolutely  convince  one  that  the  harmony  is 
not  quite  as  much  the  result  of  chance  as  of  design. 

Assuming  that  the  parts  of  the  body  were  employed  by  many 
ancient  races  as  the  basis  of  measures  of  length,  it  is  desirable  to 
ascertain  how  these  were  united  into  a  system  and  how  such  a 
system  spread.  It  is  usual  to  credit  the  origin  of  systems  of* 
weights  and  measures  to  Babylon  or  Egypt,  the  systems  of  both 
countries  showing  a  common  source,  and  there  being  various 
remains,  literary  and  archaeological,  on  which  have  been  based 
explanations  of  the  origin  of  all  ancient  measures.  Thus  the 
great  pyramid  of  Ghizeh,  dating  from  about  4000  B.C.,  by  some  has 


10       EVOLUTION   OF   WEIGHTS   AND   MEASURES 

been  thought  to  have  an  important  bearing  on  metrology,  and  has 
figured  in  many  discussions  and  theories,  since  by  its  dimensions 
and  inscriptions  it  supplies  data  which  are  susceptible  of  various 
interpretations.  Thus  Paucton  and  Jomard,1  two  distinguished 
metrologists  of  the  eighteenth  century,  assumed  that  the  side  of  the 
pyramid  represented  a  fraction  of  a  degree  of  the  earth  just  as 
the  French  scientists  based  the  meter  on  a  fraction  of  the  earth's 
quadrant ;  while  later  Prof.  Piazzi  Smyth2  and  Lieut.  C.  A.  L. 
Totten3  derived  the  Anglo-Saxon  weights  and  measures  directly 
from  its  dimensions.  These  theories,  as  well  as  the  idea  that  the 
great  pyramids  played  an  important  part  in  ancient  astronomy, 
have  been  amply  controverted,  and  according  to  the  opinion  of 
Lieut.-Gen.  Sir  Chas.  Warren4  in  the  light  of  the  most  recent 
investigations,  "  The  Pyramid  is  simply  a  record  of  the  measures, 
/  linear,  capacity,  and  weight,  which  were  in  use  in  former  days." 
There  is  nothing  astronomical  about  it  except  its  orientation  and 
the  direction  of  its  great  gallery  to  a  point  in  the  northern  sky. 

There   were,   however,   other   great   structures   in   Egypt   and 

/Babylonia  in  which  stone  and  brick6  of  regular  dimensions  were 

/used,  and  even  in  the  earliest  times  of  which  we  have  record  it 

/seems  conclusive  that  there  must   have  existed  fairly  complete 

systems  of  weights  and  measures. 

According  to  the  Jewish  tradition  given  in  Josephus,  we  are 
informed  in  the  quaint  language  of  Dr.  Arbuthnot,  "  that  Cain 
was  the  first  monied  man,  that  he  taught  his  band  luxury  and 
rapine,  and  broke  the  public  tranquillity  by  introducing  the  use  of 
weights  and  measures."6  What  happened  in  the  land  of  Nod, 

1  Paucton,  Metrologie,  ou  Trait6  des  Mesures,  Poids  et  Monnoies  (Paris,  1780); 
Jomard,  Memoire  sur  le  Systeme  Metrique  des  Anciens  Egyptiens  (Paris,  1817). 

2C.  Piazzi  Smyth,  Life  and  Work  at  the  great  Pyramid  (Edinburgh,  1867) ;  Our 
Inheritance  in  the  great  Pyramid  (London,  1864).  These  works  and  Professor 
Smyth's  theories  are  discussed  by  Dr.  F.  A.  P.  Barnard  in  Proceedings  Am. 
Metrological  Society  (New  York),  vol.  iv.,  1884,  pp.  197-219. 

3 Charles  A.  L.  Totten,  An  Important  Question  in  Metrology  (New  York,  1884). 

4 Warren,  "The  Ancient  Standards  of  Measure  in  the  East,"  p.  222,  Palestine 
Exploration  Fund  Quarterly,  1899. 

5  In  Babylonia  square  bricks  were  used  which  measure  13  inches  on  each  edge, 
or  £  of  the  double  cubit  as  given  by  the  Gudea  Scale  (see  p.  14). 

6  Arbuthnot,  p.  1,  Tables  of  Ancient  Coins  (London,  1754). 


THE   SCIENCE   OF   METROLOGY  11 

whither  Cain  had  wandered  with  his  band  and  where  he  founded 
his  city  (Genesis  iv.  16  and  17),  soon  must  have  become  universal, 
for  we  find  the  dimensions  of  the  ark  as  Noah  was  told  to  construct 
it  given  in  cubits  (Genesis  vi.  15). 

Apart  from  such  traditions  and  scriptural  legends  we  know 
from  brick  tablets  and  other  remains  that  weights  and  measures 
in  some  form  or  other  flourished  in  Babylonia  and  Egypt,  and 
that  the  systems  of  the  two  countries  doubtless  had  a  common' 
origin.  Although  it  cannot  be  definitely  proved  it  is  likely  that 
this  origin  was  Babylonian,  and  much  that  has  been  written  on 
ancient  metrology  is  based  on  this  view.  Hommel,  in  speaking  of 
the  Babylonian  metrology,1  states  that  from  it  "  admittedly  all 
the  ancient  metrological  systems  (that  of  ancient  Egypt  included) 
were  derived."  This  is  also  the  opinion  of  Dr.  Brandis.2  Assum- 
ing such  to  be  the  case,  we  are  brought  at  once  face  to  face  with 
a  great  diversity  of  opinion  on  the  point  as  to  whether  a  well- 
developed  and  scientific  system  of  weights  and  measures  existed 
in  Babylonia,  from  which  were  derived  the  weights  and  measures 
of  the  adjoining  nations,  and  which,  through  trade  and  commerce, 
spread  over  the  then  civilized  earth,  or  whether  various  systems 
of  weights  and  measures  came  into  existence  separately  in 
different  countries  and  gradually,  with  the  development  of  civi- 
lization and  under  similar  conditions,  spread  abroad  and  became 
more  or  less  assimilated.  The  first  is  the  point  of  view  of 
Boeckh 3  and  the  members  of  a  distinguished  school  of  Conti- 
nental archaeologists  and  metrologists,  and  from  available 
monumental  and  literary  remains  with  endless  patience  and 
ingenuity  they  have  evolved  theories  so  scientifically  constructed 
that  they  excite  admiration  if  they  do  not  convince.  On  the 
other  hand  there  are  a  number  of  students  of  archaeology  who 
dispute  the  scientific  basis  on  which  such  systems  are  constructed, 
and  deny  that  requisite  knowledge  and  mental  ability  for  such 
scientific  reasoning  and  construction  was  possessed  by  these  early 

1  See  article  "  Babylonia,"  Hastings'  Dictionary  of  the  Bible  (New  York,  1903), 
vol.  i.  p.  218. 

2  See  J.  Brandis,  Das  Munz-  Maass-  und  Gewichlswesen  in  Vorderasien  bis  auf 
Alexander  den  Orossen  (Berlin,  1866). 

3  Boeckh,  Metrologische  Untersuchungen  fiber  Oewichte,  Munzfiisse  und  Masse  des 
Alterthums  (Berlin,  1838). 


12       EVOLUTION   OF   WEIGHTS   AND   MEASURES 

peoples.  They  claim  that  weights  and  measures  from  some 
early  body  measures  and  natural  standards  developed  according 
to  the  needs  of  the  people  and  depended  on  widely  understood 
ratios  and  rules  of  exchange  rather  than  on  any  scientific 
basis. 

In  considering  the  first  point  of  view  it  is  necessary  to  assume 
that  considerable  mathematical  and  astronomical  knowledge  was 
possessed  by  the  ancient  Babylonians  and  was  used  by  them  in 
standardizing  their  weights  and  measures.  In  other  words,  from 
ancient  and  arbitrary  measures,  doubtless  of  the  body,  they 
f  developed  such  a  system  as  was  early  required  by  the  demands 
'  of  their  scientific  work  in  astronomy  and  their  active  building 
operations.  As  measuring  is  essential  to  all  scientific  work,  it  is 
not  to  be  doubted  that  its  importance  was  thus  early  recognized, 
and  in  conjunction  with  their  system  of  numerical  notation  a 
permanent  system  was  arranged.  This  was  also  brought  into 
direct  relation  with  their  astronomical  work,  which  was  by  no 
means  inconsiderable  for  these  early  times.  In  the  course  of 
their  observations  it  was  ascertained  that  at  the  equinox  the 
apparent  diameter  of  the  sun  on  the  horizon  was  -g-^  of  the  half 
circle.  Furthermore,  by  using  a  water  clock,  where  water  was 
allowed  to  flow  through  a  small  orifice  from  one  jar  into  another,  it 
was  found  that  the  amount  received  in  the  twelve  hours  between 
sunrise  and  sunset  was  360  times  as  much  as  when  the  sun  was 
traversing  a  distance  equal  to  its  own  diameter  or  two  minutes  of 
time.1  This  afforded  an  accurate  method  of  measuring  time,  and 
formed  the  foundation  of  the  sexagesimal  system  which  was  the 
underlying  principle  of  all  Babylonian  metrology  and  harmonized 
perfectly  with  their  system  of  numeration.  This  idea  naturally 
involved  the  division  of  the  circle  into  360  degrees,  or  rather  720 
parts,  which  has  continued  to  the  present  day,  and  the  important 
geometrical  fact  that  the  radius  is  equal  the  chord  of  one-sixth 
the  circumference  was  also  well  known  at  this  time.2 

1  L.  Ideler,  "  Ueber  die  Sternkunde  der  Chaldaeer,"  Abhandl.  der  k.  Akad. 
Wissenschaft  in  Berlin,  1814-1815,  p.  214.  Referring  to  Cleomedes  Cyclom. 
(On  the  Circular  Theory  of  the  Heavenly  Bodies),  1.  11.  p.  75  ed.  Balfor ; 
Proclus  Hypotyp.  p.  41  (ed.  Basil.  1540-4) ;  Pappus,  especially  in  his  Com- 
mentary on  the  Fifth  Book  of  the  Almagest  of  Ptolemy. 

2Hommel,  article  "Babylonia,"  Hastings'  Dictionary  of  the  Bible  (New  York, 
1903),  vol.  i.  p.  219. 


THE   SCIENCE   OF   METROLOGY  13 

By  some  authorities  it  was  believed  that  the  water  jar  referred 
to  above  was  also  used  as  a  measure  of  capacity,  and  that  it  was 
divided  on  a  duodecimal  basis  corresponding  to  the  hour  division. 
It  was  then  assumed  that  from  a  cube  equal  to  such  a  volume 
the  unit  of  length  was  derived  by  taking  the  length  of  one  of  its 
edges,  which  was  the  Babylonian  foot,  and  bore  a  natural  relation 
to  the  cubit.  This  unit  of  volume*  when  filled  with  water  gave 
the  Babylonian  talent,  from  which  other  units  of  the  same  name 
were  derived.  This  theory,  however,  which  was  supported  for 
many  years,  has  been  abandoned,  and  it  is  believed  that  the  unit 
•of  weight  was  derived  from  the  unit  of  length,  just  as  is  done  in 
the  modern  metric  system. 

The  relation  of  numbers  and  linear  distances  in  Babylonian  j 
measures  is  best  derived  from  a  study  of  the  Senkereh  Tablet, 
which  dates  back  to  about  2500  B.C.,  and  was  discovered  in  1850 
in  a  small  Arab  village  on  the  site  of  the  ancient  city  of  Larsam 
or  Larsa.  It  is  now  in  the  British  Museum,  and  affords  con- 
siderable information  as  to  the  Babylonian  measures  and  the 
methods  of  computation.  It  is  a  clay  tablet,  on  one  side  of 
which  are  the  fractions  and  multiples  of  the  ell  or  cubit,  and  on 
the  other  are  the  squares  and  cubes  of  the  cubit  from  1  to  40.1 
This  tablet  has  received  the  attention  of  a  number  of  scholars, 
including  the  late  Professor  Eawlinson,  and  the  sexagesimal 
character  of  the  measures  has  been  clearly  demonstrated.  In 
connection  with  the  scale  of  Gudea,  to  be  described  a  few  lines 
below,  it  has  been  examined  by  the  Rev.  W.  Shaw-Caldecott,  who 
concludes  that  "  The  breadth  of  the  hand-palm  conventionalized 
was  the  fundamental  of  all  length  measures,"  and  "  That  there 
were  three  ell  (cubit)  lengths  in  simultaneous  use,  each  probably 
in  a  different  kind  of  trade  like  our  own  Troy  and  avoirdupois 
weights."  2 

1Hommel,  article  "Babylonia,"  Hastings'  Dictionary  of  the  Bible  (New  York, 
1903),  vol.  i.  p.  218. 

2 Shaw-Caldecott,  "Linear  Measures  of  Babylonia  about  2500,"  p.  263,  Journal 
Royal  Asiatic  Society,  1903,  London.  In  this  article  the  characters  on  the 
tablet  are  reproduced.  See  also  R.  Lepsius,  "  Der  Baby lonisch- Assy rischen 
Langenmasse  nach  der  Tafel  von  Senkereh,"  in  the  Abhandlungen  der 
Koniglichen  Alcadernie  der  Wissenschaften  zu  Berlin,  1877.  With  this  article 
is  printed  a  photographic  reproduction  of  the  tablet,  together  with  a  recon- 
struction. 


14       EVOLUTION   OF   WEIGHTS   AND   MEASURES 

Accordingly  from  the  tablet  Mr.  Shaw-Caldecott  derives  the 
following  units  and  proportions  : 


Line  -  =  ^-^j  of  a  palm. 

Sossus      -  -  =  -fc 

Twentieth  of  a  palm  =  ^          „ 

Twelfth  of  a  palm  =  ^ 

Third  of  a  palm,  or  digit  =  ^            „ 

Palm. 

Small  ell  (cubit)  -  =3  palms. 

Medium  ell  (cubit)  -  =  4  palms. 

Large  ell  -(cubit)  -  =5  palms. 

Small  reed  -  =  4  small  ells  (cubits). 

Medium  reed    -  =  6  medium  ells  (cubits). 

Large  reed  -  =6  large  ells  (cubits). 

While  the  Senkereh  Tablet  establishes  the  ratios  between  the 
various  units  yet  it  does  not  afford  any  information  as  to  their 
absolute  value,  and  for  this  recourse  is  had  to  a  tablet  forming 
part  of  a  statue  discovered  in  1881  at  Telloh  in  southern 
Babylonia,  not  far  from  Senkereh,  by  M.  E.  de  Sarzec,  and 
now  in  the  Louvre.1  It  dates  from  about  the  same  period  as 
the  Senkereh  Tablet,  and  represents  King  Gudea  in  a  position 
of  prayer,  and  holding  on  his  knees  a  slab  of  stone  on  which 
is  engraved  the  ground  plan  of  a  palace,  a  graving  tool,  and  a 
double  line,  the  latter  being  cut  near  the  outer  edge  and  being 
crossed  by  a  number  of  indentations  or  cuts.  This  unmistakably 
is  a  scale,  and,  furthermore,  it  is  the  oldest  scale  that  has  been 
discovered  up  to  the  present  time.  By  assuming  that  it  is 
the  same  size  as  the  scale  of  linear  measures  then  in  use,  and 
by  applying  the  proportions  obtained  from  the  Senkereh  Tablet, 
it  is  possible  to  obtain  the  lengths  of  the  various  units  in  terms 
of  modern  equivalents,  preserving  the  decimal  and  duodecimal 
division  characteristic  of  the  Babylonian  arithmetical  system. 
Thus  we  have  the  handbreadth  or  palm  equal  to  99-99*6  mm. 
(3'9-4'l  inches),  and  the  cubit  composed  of  five  handbreadths 

JE.  de  Sarzec,  Dtcouvertes  en  Chaldee,  1884-1889,  PI.  15.  See  also  Shaw- 
Caldecott,  loc.  cit.  See  also  Toy,  "The  Book  of  the  Prophet  Ezekiel  "  (Part  12, 
Sacred  Books  of  the  Old  Testament,  "Polychrome  Bible")  (New  York,  1889), 
Notes,  pp.  179-180  for  illustrations  and  description. 


THE   SCIENCE   OF   METROLOGY  15 

equal  to  495  mm.  (19*483  inches),  and  also  in  early  and  wide-  ,/ 
spread  use  a  double  cubit  twice  this  length  or  990  mm.  (38*976- 
inches).  This  latter  unit  is  of  interest  on  account  of  its  close 
approximation  to  the  modern  meter  of  1000  mm.,  and  also  on 
account  of  the  fact,  first  discovered  by  Lehmann,  that  it  is  almost 
exactly  the  length  of  the  second's  pendulum  for  the  latitude  of 
Babylon  (31  degrees  north,  at  which  point  the  theoretical  length 
of  a  second's  pendulum  would  be  992*35  mm.).  Consequently 
he  argues  that  the  theory  of  the  pendulum  must  have  been 
known  to  the  early  Babylonians,  who  doubtless  derived  it  from 
the  plumb-line,  which  must  have  been  employed  in  their 
building  operations.1  This  fact,  however,  cannot  be  regarded 
as  more  than  a  mere  coincidence,  and  while  it  is  most 
interesting  it  is  not  considered  possible  that  such  an  important 
physical  principle  should  have  been  known  at  so  early  a  day 
and  then  allowed  to  lapse  from  human  knowledge  until  the 
time  of  Galileo. 

Multiplying  the  great  cubit  by  6  the  "  reed "  was  obtained,, 
and  by  taking  12  great  cubits  the  gar.  To  form  the  ush  or 
stadion  60  gar  were  required,  and  30  ush  made  a  parasang  or 
kasbu,  which  was  equivalent  to  about  21  kilometers.  These 
longer  linear  measures  are  again  connected  with  the  measure 
of  time,  as  360  great  cubits  represented  the  distance  an  average 
walker  could  accomplish  in  four  minutes,  while  the  great  kasbu 
of  21,600  cubits  was  the  distance  traversed  during  a  night  watch 
of  four  hours  or  ^  of  a  day,  and  the  small  kasbu  would  be  one 
half  of  this  distance. 

Measures  of  area  constructed  by  squaring  the  linear  measures- 
are  also  claimed  for  the  Babylonians,  and  here  again  the  sexa- 
gesimal ratio  was  preserved ;  thus  180  she  made  a  gin,  which  was- 
possibly  equal  to  a  square  cubit.  A  "  garden  "  (sar)  was  com- 
posed of  60  gin,  and  1800  gardens  formed  a  "field"  (gan).  But 
the  Babylonians,  in  common  with  other  Asiatic  nations,  also 
employed  for  measuring  land  the  amount  of  seed  required  to 

1  Lehmann,  p.  89,  "  Ueber  das  babylonische  metrische  System  und  dessen 
Verbreitung,"  Verh.  der  Physikalischen  Gesellschaft  zu  Berlin  (Berlin,  1890),  vol. 
viii.  pp.  81-101  ;  also  in  abstract,  pp.  167-168,  vol.  Ixi.,  Nature  (London,  1889). 
In  this  connection  a  paper  by  the  same  author,  "  Alt-babylonisches  Maass  und 
Gewicht  und  deren  Wanderung,"  Zeitschrift  fur  Ethnologie  (Berlin,  1889),  pp.  245- 
328,  may  also  be  consulted  with  profit/ 


It)       EVOLUTION   OF   WEIGHTS   AND   MEASURES 

•sow  a  field,  and  statements  based  on  this  idea  are  found  in  many 
old  Assyrian  documents.1 

The  Babylonian  capacity  measures  started  with  a  cube  whose 
«dge  was  a  handbreadth  in  length  (99-99'6  mm.),  and  which 
when  filled  with  water  gave  the  unit  of  weight,  the  great  mina, 
which,  occupying  as  it  does  almost  the  volume  of  a  cubic  deci- 
meter, would  correspond  quite  closely  with  the  modern  kilogram. 
Such  a  capacity  measure  was  known  as  the  Jca,  and  was  nearly 
the  equivalent  of  the  modern  liter.  As  multiples  of  the  Jca 
there  was  the  gur,  which  was  composed  of  either  360  or  300 
of  the  smaller  units,  there  being  not  only  two  such  gurs  but 
a  third  divided  into  180  parts  and  based  on  a  double  Jea,  from 
which  the  Hebrews  probably  obtained  their  kor,  which  they 
divided  into  180  kab.  Likewise  in  the  subdivision  of  the 
Babylonian  measures  there  was  the  gin  or  -£$  of  a  ka,  which 
in  the  Hebrew  system  was  paralleled  by  the  hin. 

The  relation  between  the  capacity  and  weight  we  have  already 
seen  in  the  case  of  the  great  mina,  which  weighing,  as  it  did, 
between  982  '4  and  985*8  grams  gives  a  noticeably  close  approxi- 
mation to  the  modern  kilogram.  This  great  or  heavy  mina  was 
composed  of  60  shekels,  each  of  360  she  or  grains  of  corn,  thus 
combining  in  a  system  of  weights  two  classes  of  natural  units. 
The  greater  weight  was  the  talent  composed  of  60  minas.  Such 
a  system  would  have  been  simplicity  itself,  were  it  not  for  the 
fact  that  several  systems  of  weights,  just  as  of  linear  measures, 
are  found  employed  at  the  same  time.  There  was  a  light  mina 
which  weighed  one  half  of  the  heavy  mina,  and  in  fact 
whole  light  and  heavy  systems  standing  to  each  other  in  the 
ratio  of  1  : 2  are  believed  to  have  existed,  of  which  representative 
weights  have  been  found.  Furthermore,  as  gold  and  silver, 
whose  values  were  in  the  ratio  of  40 : 3,  were  used  as  currency, 
other  systems  designed  to  accommodate  both  weight  and  value 
arose,  and  there  was  a  mina  of  gold  which  was  composed  of 
50  Units,  each  a  shekel  or  -fa  of  the  weight  mina.  Then  there 
was  a  silver  mina  which  weighed  about  -^  more  than  the  Baby- 
lonian mina  of  weight,  while  there  was  a  Phoenician  mina  which 
was  also  divided  into  50  units,  which  made  the  whole  equal  to 
^§  of  the  original  weight  mina. 

1 C.   H.  W.  Johns,  Assyrian  Deeds  and  Documents   (London,  1902),  vol.  ii. 
pp.  219-220. 


THE   SCIENCE    OF   METROLOGY  17 

The  subject  of  Babylonian  units  of  weight  is  one  of  consider- 
able complexity  on  account  of  the  fact  that  weight  and  currency 
had  so  intimate  a  relation  and  that  gold  and  silver  were  both 
standards.  Furthermore,  there  was  doubtless  legislation  stan- 
dardizing certain  other  weights  so  that  discrepancies  would  be 
found  on  that  score. 

Having  considered  such  a  carefully  erected  structure  we  must 
now  discuss  briefly  the  position  of  those  that  would  demolish 
utterly  any  such  scientific  arrangement  and  basis  for  ancient 
weights  and  measures,  and  more  particularly  any  connection 
between  the  two.  We  are  called  upon  to  proceed  further  along 
the  lines  indicated  in  the  beginning  of  this  chapter,  and  to 
observe  that  the  use  of  weights  and  measures  accompanied  the 
gradual  development  of  civilization,  and  that  exactness  in  either 
the  determination  of  units  of  measure  or  in  the  preservation  of 
standards  was  no  more  characteristic  of  the  twentieth  or  thirtieth 
•century  B.C.  than  it  was  of  the  second  or  third.  Although  the  early 
Babylonians  may  have  known  how  to  divide  time  on  a  sexa- 
gesimal basis  and  to  observe  eclipses,  yet  so  simple  a  mathematical 
process  as  obtaining  area  by  multiplying  length  and  breadth 
together  seems  to  have  been  unknown  according  to  a  study  of 
their  literary  remains,  since  for  the  measurements  of  land  areas 
the  unit  was  not  a  square,  but  a  strip  of  uniform  width.1 
Furthermore,  the  extensive  use  of  the  amount  of  seed  required 
superficial  measures.  The  most  strenuous  objection  has  been 
made  to  any  systematic  relation  and  connection  between  weights 
and  measures,  and  this  feeling  on  the  part  of  continental  scholars 
is  considered  due  to  their  intimate  knowledge  and  use  of  the 
metric  system,  which  acquired  by  them  so  readily  would  doubtless 
suggest  the  possibility  of  the  employment  of  its  fundamental 
features  by  the  ancients.  Why  several  thousand  years  should 
intervene  before  the  mind  of  man  would  return  to  such  devices, 
it  is  difficult  if  not  impossible  to  explain,  and  like  many  other 
phenomena  considered  now  so  simple,  it  is  most  natural  to 
assume  that  it  was  known  to  the  ancients,  yet  at  the  same  time 
it  is  impossible  to  prove  it.  Thus  any  such  relations  must  be 
•entirely  hypothetical,  and  the  only  arguments  to  be  advanced  in 

1C.   H.  W.   Johns,  Assyrian  Deeds  and   Documents  (London,    1902),   vol.   ii. 
pp.  219-220. 


18       EVOLUTION   OF   WEIGHTS   AND   MEASURES 

their  support  must  be  founded  on  circumstances  which  are  pro- 
bably mere  coincidences,  and  doubtless  most  delusive.  Professor 
Flinders  Petrie,  in  speaking  of  this  subject,  says : 1  "  All  that 
can  be  said  therefore  to  the  many  theories  connecting  weights- 
and  measures  is  that  they  are  possible,  but  our  knowledge  at 
present  does  not  admit  of  proving  or  disproving  their  exactitude.  "" 
Though  this  was  written  some  years  ago,  nevertheless  it  is  fair 
to  say  that  there  has  been  no  discovery  or  research  that  would 
warrant  any  different  expression  from  one  holding  Mr.  Flinders- 
Petrie's  views.  According  to  another  leading  authority,  the 
Rev.  C.  H.  W.  Johns,  who  has  carefully  examined  many  literary 
remains  of  the  old  Babylonians,  there  is  not  afforded  by  these- 
documents  any  ground  for  believing  in  any  connection  between 
Babylonian  measures  of  length  and  weight,  while  to  him 
Lehmann's  idea  of  the  double  cubit  derived  from  the  second's 
pendulum  seems  quite  ridiculous.  According  to  Ridgeway,2- 
considering  the  Hindus  as  an  ancient  people  of  culture,  with 
whose  literature  we  have  some  acquaintance,  we  find  that 
"  though  they  were  clever  mathematicians,  yet  they  fixed  their 
standards  of  weights  by  natural  seeds  in  the  good  old  primi- 
tive fashion,  and  did  not  make  the  slightest  attempt  to  find 
a  mathematical  basis  for  their  metrological  work." 

In  short,  from  this  point  of  view  the  situation  for  the- 
Babylonians,  and  indeed  for  any  other  nation  whose  claim 
for  a  similar  priority  should  be  advanced,  may  be  summarized 
as  follows :  The  Babylonians  in  common  with  other  nations- 
from  body  measures  and  seeds  of  grain  or  other  plants  developed 
such  systems  of  measurements  as  sufficed  for  their  wants ;  their 
standards  were  arbitrary  and  changing,  but  since  they  were- 
the  leading  people  of  this  part  of  the  world  as  regards  culture,, 
their  measures  were  impressed  on  their  neighbors,  and  especially 
on  the  Phoenicians,  by  whom  as  the  chief  traders  of  this  period 
of  antiquity  they  were  spread  abroad.  There  is  no  reason  to 
believe  that  the  weights  were  preserved  in  any  kind  of  purity,, 
/  nor  is  there  any  reason  to  see  why  this  should  have  occurred,, 
and  when  we  consider  the  variation  in  weights  and  measures 

1W.  M.    Flinders   Petrie,  article   "Weights  and    Measures,"   Encyclopaedia 
Urilannica,  9th  ed.  vol.  xxiv.  p.  482. 
2  Ridge  way,  Origin  of  Metallic  Coinage  and  Weights,  Cambridge,  1892,  p.  178. 


THE   SCIENCE   OF   METROLOGY  19 

during  more  recent  centuries  with  their  scientific  men  and 
methods,  their  mints  and  their  standards,  not  to  mention 
government  regulation,  as  exampled,  say,  in  Great  Britain,  it 
is  not  natural  to  believe  that  those  ancient  units  could  have 
been  fixed  to  any  basis  with  scientific  exactness,  i  Such  mere 
coincidences  as  that  a  cubic  foot  of  water  weighs.  1000  ounces, 
and  that  a  British  imperial  gallon  of  water  at  temperature  of 
maximum  density  weighs  ten  pounds,  if  put  back  into  the  past 
would  form  a  far  better  basis  upon  which  to  form  decimal 
and  other  systems  than  many  of  the  facts  that  have  been 
employed  by  scientific  metrologists.1 

As  an  argument  of  this  kind  depends  largely  upon  quoting 
authorities,  and  dealing  in  detail  with  apparent  and  actual 
inconsistencies,  it  is  manifestly  impossible  to  do  justice  to  it  in 
these  few  paragraphs ;  but  reference  to  Johns  and  Ridgeway 
in  the  volumes  quoted  will  amply  repay  the  student  interested 
in  this  phase  of  archaeology  and  metrology,  as  by  both  authors 
the  case  is  stated  most  ably  and  critically. 

The  Jews,  unlike  their  neighbors  in  Babylonia  and  Assyria, 
were  not  a  people  of  scientific  tastes,  and  their  weights  and 
measures  were  derived  largely  from  the  nations  whose  territory 
they  adjoined,  consequently  it  is  not  natural  to  expect  much 
uniformity  of  weights  and  measures  among  them.  Indeed,  there 
are  indications  that  there  were  at  a  single  time  among  the 
Israelites  as  many  as  three  different  and  distinct  units  of  weight, 
Babylonian,  Syrian,  and  Phoenician,  and  in  each  case  there  was 
both  a  heavy  and  a  light  system  standing  towards  each  other  as 
two  to  one.  Undeniably  there  were  Egyptian  influences  on  the 
Hebrew  weights  and  measures,  but  far  more  is  due  to  Babylon, 
as  the  civilization  of  that  country  was  predominant  in  Canaan 
up  to  the  fifteenth  century  B.C.  according  to  records  in  the 
Tel-el-Amarna  correspondence,  and  this  predominance  carried 
with  it  undoubtedly  the  Babylonian  weights  and  measures.  By 
the  eighth  century  B.C.  ,  however,  the  Israelites  had  a  legal  system 
of  weights  and  measures,  but  long  before  this  they  were 
accustomed  to  their  use,  as  when  Abraham  bought  the  field  of 
Ephron  he  "weighed  to  Ephron  the  silver"  (Gen.  xxiii.  16). 

1  Flinders  Petrie,  article  "Weights  and  Measures,"  Encyclopaedia  Britannica, 
9th  ed.  vol.  xxiv.  p.  482. 


20       EVOLUTION   OF   WEIGHTS   AND   MEASURES 

In  fact,  the  Israelites  became  so  accustomed  to  the  use  of  the 
balance  and  of  measures  that  they  began  to  employ  false  weights 
and  wrong  measures,  with  the  result  that  not  once  but  many 
times1  their  prophets  and  teachers  are  forced  to  emphasize  honest 
dealing  in  matters  of  measurements  and  the  weighings  of  daily 
life.  The  chief  unit  of  length  of  the  Hebrews  was  the  cubit, 
and  with  it  were  employed  the  usual  body  measures,  such  as 
finger  breadths  or  digits,  palms,  spans,  and  fathoms  and  reeds. 
For  these  measures  we  have  practically  no  data  for  determining 
their  equivalents,  and  Professor  A.  E.  S.  Kennedy  expresses  the 
opinion  "  that  reliable  data  for  the  exact  evaluation  of  the 
Hebrew  cubit  do  not  exist."2  In  fact,  values  from  16  to  25'2 
inches  have  been  proposed  for  this  unit,  and  by  many  it  is 
believed  that  there  were  two  cubits,  one  the  "  cubit  of  man " 
of  six  handbreadths,  and  also  "  a  cubit  and  an  handbreadth  "  or 
seven  handbreadths,  which  was  used  in  the  construction  of  the 
temple  (Ezekiel  xl.  5).  This  would  correspond  to  similar  cubits 
of  the  Egyptians,  and  there  is  reason  for  believing  that  the 
weights  and  measures  of  the  two  nations  were  intimately  con- 
nected, if  not  quite  similar  at  the  time  of  the  Exodus,  but  like 
many  other  points  in  metrology  it  is  not  possible  to  bring 
forward  absolute  proof.  For  the  measurement  of  area  the 
Hebrews  employed  generally  the  amount  of  seed  required  to 
sow  the  land,  or  the  amount  of  ground  that  could  be  ploughed 
by  a  yoke  of  oxen,  the  latter  unit  being  the  zemed,  which  in  the 
Old  Testament  is  translated  by  acre.3  This  is  thought  to  be  an 
area  equivalent  to  the  Egyptian  aroura,  which  was  a  square  100 
cubits  on  each  side. 

The  capacity  measures  of  the  Hebrews  for  both  wet  and  dry 
commodities  were  arranged  upon  a  systematic  basis  which  has  in 
not  a  few  cases  been  obscured  by  imperfect  translation  in  the 
English  Bible.  The  relation  of  the  different  measures  is  expressly 
stated  in  Ezekiel  (xlv.  11  et  seq.),  where  we  learn  that  the  ephah 
and  bath  were  one  and  the  same  unit,  the  former  being  used  for 

1  Leviticus  xix.  35  et  seq.     Deuteronomy  xxv.  13-16.     Ezekiel  xlv.  9-14.     Amos 
viii.  o.     Hosea  xii.  7.     Micah  vi.  10.     Proverbs  xi.  1,  xvi.  11,  xx.  10. 

2  Kennedy,  article  "Weights  and  Measures,"  Hastings'  Dictionary  of  the  Bible 
(New  York,  1903),  vol.  v.  p.  907. 

31  Samuel  xiv.  14  and  Isaiah  v.  10. 


THE   SCIENCE   OF   METROLOGY  21 

dry  measure  and  the  latter  for  liquids.  This  unit  was  one-tenth 
of  the  homer,  a  dry  measure,  and  its  liquid  equivalent  was  the 
kor.  One-third  of  the  ephah  gave  the  seah,  which  was  divided  in 
half  and  formed  a  dry  measure  equivalent  to  the  liquid  kin. 
One-tenth  of  the  ephah  gave  a  dry  measure  known  as  the  oner, 
while  the  next  smaller  unit,  used  for  both  dry  and  liquid 
measure,  was  the  Jcab,  which  was  y^  of  the  homer  or  kor.  The 
fourth  of  the  Jcab  gave  the  log,  the  smallest  liquid  measure.  By 
taking  the  ephaJi-lath  as  equal  to  36'92  liters,  or  65  (British) 
imperial  pints,  a  value  derived  from  a  study  of  Greek  and 
Hebrew  literature,  the  modern  equivalents  can  be  approximated, 
though  this  equivalent  is  variously  stated  from  36'37  liters  to 
40'5  liters. 

In  considering  the  Hebrew  units  of  weight  we  must  bear  in 
mind  what  has  been  stated  about  the  Babylonian  units  and  their 
fundamental  proportions,  where  the  talent  was  equal  to  60  minas, 
each  composed  of  60  shekels,  or  in  the  case  of  the  gold  mina  of 
50  shekels.  There  was  the  heavy  and  the  light  systems,  stand- 
ing in  the  ratio  of  2:1,  and,  as  we  have  said  above,  systems 
based  on  Babylonian,  Syrian,  and  Phoenician  standards.  Here 
of  course  it  must  be  remembered  that  the  units  of  weight  were 
also  units  of  currency,  and  to  this  fact  is  due  in  no  small  degree 
much  of  the  variation  in  the  standards.  The  shekel  was  for  the 
Hebrews  the  principal  unit,  and  in  the  three  different  systems 
mentioned  from  literary  evidence  and  actual  weights  the  follow- 
ing values  have  been  assigned : 

Babylonian  unit,  -          -      252  grains. 

Syrian  unit,  -     320     „ 

Phoenician  unit,  -      224      „ 

The  Hebrews'  weights  without  doubt  were  not  preserved  in 
anything  like  purity,  and  besides  showing  the  effect  of  their 
Babylonian  origin,  in  later  times  there  are  evidences  of  Persian, 
Greek,  and  Eoman  influences,  so  that  our  only  means  of  iden- 
tifying them  consists  largely  in  the  connections  established  by 
the  later  Hebrew  and  the  Greek  and  Latin  authors.  The 
weights  of  the  Bible  have  received  considerable  study,  and  the 
only  warrant  for  dismissing  the  subject  here  so  summarily  is 
that  each  separate  phase  demands  detailed  treatment  and  a 


22       EVOLUTION   OF   WEIGHTS   AND   MEASURES 

critical  examination  of  authorities.  Furthermore,  the  absence 
of  positive  conclusions  which  can  be  stated  definitely  relieves 
us  of  the  necessity  for  fuller  discussion  in  this  brief  historical 
sketch.1 

In  the  study  of  Egyptian  measures  there  is  considerable  data 
for  the  metrologist,  which  is  in' the  form  of  literary  remains,  such 
as  papyri,  monuments  of  one  form  or  other  from  the  Great  Pyra- 
mid of  Ghizeh  to  wall  carvings,  and  actual  wooden  and  stone 
scales.  In  the  main  there  is  little  variation  from  the  measures 
of  Babylonia  and  many  points  of  similarity  both  in  the  weights 
and  measures  and  in  the  etymology  of  the  words  expressing  them 
are  seen,  which  indicate  a  common  origin  for  the  weights  and 
measures  of  both  nations,  and  aid  in  substantiating  any  theory 
based  on  the  assumption  that  there  was  a  definite  parent  system. 
There  is  a  correspondence  between  the  royal  or  building  cubit  of 
seven  palms' and  28  digits  which  has  been  constructed  from  the 
measurements  of  temples  and  other  buildings  in  Egypt  and 
the  so-called  sacred  or  building  cubit  of  the  Babylonians.  Actual 
representatives  of  the  former  have  been  found  in  the  nilometer 
cubit  of  Elephantis,  and  the  wooden  scale  of  Amenoemopht  from 
the  necropolis  at  Memphis,  and  other  scales  both  wooden  and 
stone.2  A  mean  value  obtained  from  actual  scales  and  measure- 
ment gives  for  the  modern  equivalent  of  the  cubit  525  mm. 
or  20'63  inches. 

'/'  With  this  royal  cubit  was  also  used  a  natural  or  common 
(short)  cubit  which  was  of  the  length  of  six  palms,  and  cor- 
responded to  the  Greek  cubit.  The  Egyptians  employed  the 
various  subdivisions  on  the  basis  of  the  body  measures,  but  they 
do  not  seem  to  have  used  either  the  foot  or  the  fathom.  All  of 
these  can  be  found  expressed  in  their  hieroglyphics,  and  are  found 
in  many  of  the  ancient  papyri.  For  long  measure  there  was  the 

1  For  further  information  and  detailed  references  the  following  authorities  may 
be  consulted :   Kennedy,  article  "  Weights  and   Measures,"  in   Hastings'  Dic- 
tionary of  the  Bible  (New  York,  1902),  vol.  v.  p.  901  et  seq.  ;  G.  F.  Hill,  article 
"Weights  and  Measures,"  in  Encyclopaedia  Biblica  (New  York,  1903),  vol.  iv. 
p.  5292  et  seq.     These  and  allied  articles  contain  full  and  detailed  bibliography. 
See  also  C.  R.  Conder,  "Hebrew  Weights  and  Measures,"  Palestine  Exploration 
Fund  Quarterly  Statement,  1902. 

2  For  description  and  illustrations,  see  Lepsius,    Ueber  die  alt-aegyptische  Elle 
und  ihre  Eintheilung  (Berlin,  1865). 


THE   SCIENCE   OF   METROLOGY  23 

j  which  was  equal  to  100  cubits,  and  was  represented  by  a 
hieroglyphic  of  a  coil  of  cord,  as  undoubtedly  a  line  and  reel  were 
used  for  such  measurements,  just  as  Ezekiel  (xl.  3)  speaks  of  a 
*' flaxen  line"  and  "measuring  rod"  being  used  in  measuring  the  new 
temple,  and  Jeremiah  (xxxi.  32)  mentions  the  use  of  the  "  measur- 
ing line"  in  surveying  land.  For  very  long  distances  the  Egyptians 
had  a  measure,  the  ater,  equal  to  from  30  to  60  or  more  stades 
and  known  to  the  Greeks  as  a  sckoemis,  but  it  is  expressly  stated 
by  Strabo  that  it  varied  in  different  parts  of  the  country.  It  is  / 
•of  some  importance,  however,  as  it  figures  in  geographical  descrip- 
tions of  Egypt,  and  has  been  actually  found  marked  on  the 
Memphis-Faium  road.1  The  Egyptians  had  a  series  of  square 
measures  with  a  chief  unit  in  the  set  equal  to  the  Greek  aroura 
and  comprising  a  square,  a  khet,  or  100  royal  cubits  on  each  side, 
the  latter  unit  forming  the  basis  of  land  measurement.  For 
•capacity  the  principal  measure  was  the  hekt,  which  was  equal  to 
^  of  the  cubit  cubed,  while  for  corn  there  was  employed  the 
khar  ("  sack  ")  of  20  hekt  until  superseded  by  the  sack  of  16  hekt 
or  the  Greek  medimnus,  at  or  before  the  XVIII.  dynasty.  After 
the  Macedonian  conquest  the  latter  measure  was  halved  to  form 
the  artaba,  doubtless  to  conform  with  a  measure  introduced  from 
Persia.  Then  there  was  the  henu  or  -^  of  the  hekt,  used  both 
for  solids  and  liquids,  as  well  as  numerous  other  measures. 
According  to  Griffiths,  whom  we  have  followed  in  this  description 
of  Egyptian  weights  and  measures,2  the  Egyptian  measures  were 
not  derived  from  a  cubit  or  fraction  of  a  cubit  cubed,  but  it  is 
probable  that  the  cubic  idea  was  introduced  a  considerable  time 
after  the  measures  had  been  quite  definitely  fixed  by  custom. 

In  striking  contrast  to  the  many  allusions  to  measures  that  are 
found  in  the  early  papyri  there  is  a  lack  of  information  as  regards 
weights.  That  weights  existed  and  were  used  is  known  from  a 
large  number  of  weights  that  have  been  discovered,  and  from  the 

1  Flinders  Petrie  in  Encyclopaedia  Britannica,  9th  ed.  vol.  xxiv. ,  article 
*'  Weights  and  Measures,"  p.  483.  Also  id.,  Season  in  Egypt,  pi.  xxvi.  (London, 
1888). 

2F.  L.  Griffiths,  "Notes  on  Egyptian  Weights  and  Measures,"  Proceedings 
Society  of  Biblical  Archaeology  (London),  vol.  xiv.  p.  403  et  seq.,  1892.  In  this 
paper  will  be  found  the  various  hieroglyphics  and  a  full  explanation  of  their  use. 
See  also  a  continuation  of  this  paper  by  the  same  author  in  same  Proceedings, 
vol.  xv.  p.  301,  1893. 


24       EVOLUTION   OF   WEIGHTS   AND   MEASURES 

fact  that  balances  are  shown  in  the  decorations  of  the  tombs  of 
the  V.,  XL,  XII.,  and  XVIII.  dynasties.  In  fact,  the  earliest 
known  weight  is  inscribed  with  the  cartouche  of  Chufu  (IV. 
dynasty),  the  builder  of  the  Great  Pyramid  at  Ghizeh,  whose 
date  was  approximately  4000  B.C. 

The  use  of  the  balance  in  the  earliest  times  was  probably  con- 
fined to  exchange  of  gold  and  silver,  and  it  doubtless  was- 
invented  for  this  purpose.  But  one  reference  is  found  to  weights- 
before  the  XVII.  dynasty,  and  only  gold,  silver,  copper,  and  lapis 
lazuli  were  weighed  even  at  that  time,  as  no  mention  of  weight  is- 
made  in  the  so-called  medical  papyri,  where  it  would  be  natural 
to  find  such  an  allusion  were  weights  in  current  use.  Their 
application  increased  slowly,  and  by  the  time  of  the  Ptolemies, 
incense,  honey,  and  drugs,  as  well  as  metals  and  precious  stones,. 
were  weighed.  About  the  time  of  the  XVII.  dynasty  the 
deben  or  uten,  a  weight  of  1400-1500  grains,  and  its  tenth  part, 
the  kiti  (also  called  kat)  are  found  to  be  the  only  recognized 
units  of  weight  in  the  various  documents,  but  there  have  been 
found  a  wide  variety  of  actual  weights,  which  it  is  quite  impos- 
sible to  identify  either  with  any  system  or  among  themselves, 
and  which  serve  to  embarrass  the  investigator.1 

Later  the  units  of  weight  in  widespread  use  were  the  talent, 
the  mina,  and  the  shekel,  as  in  other  ancient  nations,  but  con- 
siderable diversity  is  shown,  though  in  general  plan  much  the 
same  division  was  followed  as  for  the  weights  of  the  Babylonians 
and  Hebrews  already  described.  By  some  authorities  the  basis- 
of  the  Egyptian  unit  of  weight  is  considered  to  be  a  cubic 
volume  (the  cubic  foot  or  cubit)  of  water,  but  at  all  events  there 
were  also  various  foreign  influences,  such  as  Greek  and  Asiatic 
units  of  weight,  which  produced  a  certain  amount  of  confusion, 
and  prevented  any  universal  and  single  system.  Under  Ptolemy 
Lagos  (d.  283  B.C.),  however,  certain  reforms  of  weights  and 
measures  were  effected  that  resulted  in  perpetuating  the  old 
Egyptian  system,  and  the  talent  weights  thus  defined  were 
known  subsequently  as  the  Alexandrian  talents.  These  were 

1  Flinders  Petrie,  article  "Weights  and  Measures,"  Encyclopaedia  Britannica, 
9th  ed.  vol.  xxiv.  p.  486.  Griffiths,  loc.  cit.  p.  435,  and  vol.  xv.  p.  307.  A.  E. 
Weigall,  "Some  Egyptian  Weights  in  Professor  Petrie's  Collection,"  Proceedings 
Society  Biblical  Archaeology  (London),  vol.  xxiii.  p.  378,  1901. 


THE   SCIENCE   OF   METROLOGY  25 

of  two  classes,  each  of  which  were  divided  into  60  minas  of 
50  shekels  or  100  didrachms  eack,  but  the  greater  Alexandrian 
talent  of  copper  or  brass  weighed  just  twice  as  much  as  the 
smaller  or  lesser  Alexandrian  talent  of  silver.  The  former  was 
divided  into  125  pounds  by  the  Eomans  when  they  occupied 
Egypt,  while  the  miria  derived  from  the  lesser  talent  was 
divided  into  12  ounces  (unciae),  and  weighing  as  it  did  5460 
grains,  it  became  the  predecessor  of  the  series  of  European 
pounds  of  which  the  Troy  pound  is  a  type.  From  one  of  these 
ounces,  if  we  may  believe  a  Syrian  authority,  Anania  de 
Schiraz,  who  wrote  in  the  sixth  century,  by  taking  the  T^j 
rt/the  carat  or  diamond  weight  was  originally  formed.1 
Pn  Greece  the  fundamental  unit  of  length  was  the  foot,  and 
while  we  find  the  cubit,  yet  it  is  the  foot  that  plays  the  principal 
partj  The  same  unit,  namely,  the  Olympian  foot,  was  found 
throughout  Greece,  though,  of  course,  there  was  necessarily 
considerable  divergence  from  any  one  value  at  different  times 
and  different  places.  fl"~A  clue  to  the  actual  lengthJ^WIftCt,  is 
found  in  the  ruins  of  the  Parthenon,  where  the  main  hall  of 
the  Temple  of  Athena  is  called,  according  to  Plutarch,2  Heka- 
tompeclos  (one  hundred  feet),  and  measurements  show  that  it 
was  100  Attic  feet  in  breadth  by  225  in  length,  these  numbers 
being  derived  from  the  ratio  of  the  breadth  to  the  length,  and  /"^\ 
giving  an  Attic  foot  equal  to  '30828  meter  or  12  '1375  inches.  \  II 
One  hundred  times  the  foot  gave  the  plethron,  which  was  \  \1/ 
squared  and  used  as  a  measure  of  area.  The  Greek  cubit,  or  1 
1^-  times  the  foot,  closely  resembles  the  natural  cubit  rather 
than  the  sacred  or  building  cubit  of  the  Babylonians  and  Egyp- 
tians, and  four  of  them  made  the  orguia  or  fathom,  that  is  the 
distance  between  the  tips  of  the  fingers  when  the  arms  were 
extended.  This  multiplied  by  100  gave  the  stadion,  originally 
the  distance  that  a  strong  man  could  run  without  stopping  for 
breath,  and  then  fixed  as  the  length  of  the  Olympian  stadion  or 
athletic  track,  which  was  600  feet  in  length.3  This  stadion  was 

JH.  W.  Chisholm,  The  Art  of  Weighing  and  Measuring  (London,  1877),  p.  42. 

2  Plutarch,  Pericles,  13. 

3  Hultsch,  Griechische  und  Romische  Metrologie,  2nd  ed.  (Berlin,  1882),  p.  33. 
This  will  be  found  a  standard   authority  in  classical  measures,  and  will  give 
text  references  to  all  authorities.     On  it  are  based  most  of  the  statements  in 
the  pages  devoted  to  Greek  and  Roman  metrology. 


-26       EVOLUTION   OF   WEIGHTS   AND   MEASURES 

.about  one  eighth  of  the  Eoman  mile,  and  this  ratio,  as  well  as  8^, 
is/used  byiStrabo  and  Polybius. 

[t  was  most  natural  that  the  measures  of  Greece  should  pass  to 
)me,  and  we  find  between  the  two  a  close  connection.  The 
principle  of  subdivision  was  duodecimal,  and  we  find  the  Greek 
foot  introduced  as  a  unit  of  length.  It,  as  well  as  the  as,  or  unit 
of  weight,  was  divided  into  twelve  unciae,  whence  our  English 
words  inch  and  ouncj^fimong  the  other  measures  of  length 
•employed  by  the  ^onRns  was  the  palmipes,  or  foot  and  hand- 
breadth  ;  and  the  cubitus  (cubit),  or,  as  it  was  also  known,  the 
ulna,  from  which  is  derived  the  French  word  aulne  and  the 
English  ell.  The  passus  or  unit  of  itinerary  measure  was 
•equivalent  to  5  Eoman  feet,  and  when  multiplied  by  1000  gave 
the  millia  passuum,  from  which  was  derived  the  mile  as  subse- 
quently used  in  Britain  and  elsewhere.  The  passm  was  a  double 
step  or  gradus,  and  was  the  distance  covered  from  the  time  when 
one  foot  was  taken  from  the  ground  until  it  was  placed  down 
.again.  For  architects  and  surveyors  there  was  a  unit  ten  feet  in 
length  known  as  a  pertica  or  decempeda,  and  the  square  of  this 
•distance  gave  the  unit  of  area  employed  in  surveying,  twelve 
times  which  gave  the  actus  or  distance  that  a  plow  would 
•encompass  in  a  single  course,  while  the  actus  multiplied  by.  two  ^ 
would  give  the  jugerum  or  Eoman  acre  ('6229  English  acre)lj 

Perhaps  the  foot  is  the  most  important  of  the  EomHIl  Uie"asures, 
las  it  not  only  extended  throughout  Europe  as  a  fundamental 
unit,  but  in  some  form  it  balT^irvived  almost  everywhere  until 
.supplanted  by  the  meterJiTn^6,  there  were  marked  variations, 
.and  the  standards  employed  were  most  arbitrary,  but  the  supre- 
macy of  the  foot  as  the  unit  of  length  was  maintained  in  Europe 
until  the  nineteenth  century.  The  connection  of  the  Eoman 
foot  to  that  of  Greece  has  already  been  shown,  but  attention 
should  be  called  to  the  fact  that  it  gradually  becdme  shorter, 
.and  in  the  time  of  Pliny  it  bore  the  relation  to  the  Greek  foot 
of  25 : 24.  There  was  also  a  foot  of  Drusus  which  was  used 
outside  of  Italy  for  measuring  land,  and  became  permanent  in 
the  countries  along  the  Ehine  and  Lower  Germany.  This  foot 
•contained  13^  Eoman  inches  or  13'1058  English  inches,  332'6  mm., 
.and  doubtless  came  to  Europe  in  some  way  from  Asia  Minor. 
Jt  is  worthy  of  note  that,  besides  persisting  in  the  Ehine 


THE   SCIENCE   OF   METROLOGY  27 

countries,   it   was   adopted   by  the  Belgic  tribes,  and   by   them  ! 
introduced  into  Britain,  where  it  endured,  as  will  subsequently 
be  shown,  until  the  fifteenth  century.1 

Greece  originally  had  as  its  standard  of  weight  the  heavier 
Babylonian  talent,  or,  speaking  more  exactly,  this  was  in  use 
in  Aegina,  and  thence  extended  into  the  Spartan  States  and  to 
Corinth,  whose  inhabitants  being  actively  engaged  in  commerce 
•did  much  to  spread  its  use.  This  talent  was  considered  equal 
to  the  weight  of  a  cube  of  water  whose  edge  was  an  Olympic 
cubit,  or  1^-  times  a  Greek  or  Olympic  foot.  By  diminishing 
the  Babylonian  talent  one-sixth,  was  obtained  the  Euboic  talent 
which  nourished  in  Greece  and  especially  in  Athens  before  the 
time  of  Solon.  This  latter  ruler  in  order  to  release  the  people 
from  the  usurers  established  by  decree  (c.  592  B.C.)  a  smaller 
talent  which  amounted  to  f  of  the  Babylonian  talent,  and 
weights  were  derived  from  it  which  alone  were  lawful  in  Athens. 
The  close  connection  between  money  and  weight  then  existing 
must  be  appreciated,  and  we  find  in  ancient  writings  that  the 
material  of  the  talent  when  used  as  currency  is  mentioned,  as  a 
talent  of  silver  (the  standard)  or  a  talent  of  gold.  The  Athenian 
talent  was  divided  into  60  minas,  each  composed  of  100  drachmas 
containing  each  6  obols  or  48  ehalkus.  There  was  a  half  miiia 
and  a  double  drachma  or  didrachm,  and  also  a  gramma  equal 
to  one  third  of  a  drachma  or  2  obols,  one  third  of  which  was  a 
lupine  whose  half  in  turn  was  a  siliqua.  The  unit  of  liquid 
measure  in  the  Athenian  system  was  the  metretes  (39'39  liters), 
which  was  subdivided  into  12  chus  or  amphora,  and  so  on  on  a 
duodecimal  basis.  The  metretes  was  ^j  of  a  Babylonian  cubic 
foot.  The  Attic  unit  of  dry  measure  was  the  medimnos,  which 
corresponded  to  Ij  metretes  or  in  modern  equivalents  to  52*53 
liters.  It  was  divided  into  six  hekteus  or  modius,  each  of  which 
was  composed  of  two  hemiekton  or  eight  choinix.  The  choinix 
was  made  up  of  two  xestes,  and  two  kotule  formed  a  xestes. 

The  Eoman  unit  of   weight   was   the   libra,  or  pound  which 1 
•corresponded    in    money    to    the    as,  and    was    divided    on    the 
duodecimal  basis  characteristic  of  the  Eomans.     Thus  the  pound 
{327*45  grams)  was  composed  of  12  unciae,  each  of  4  sicilii,  each 
•of  2   drachmas,  each  of  33  scripula,  each  of  2  dbola,  and  each  of 

1  See  p.  31. 


28       EVOLUTION   OF   WEIGHTS   AND   MEASURES 

3  siliquae,  these  names  surviving  in  modern  apothecaries* 
measure.  Its  connection  by  water  with  the  amphora  and  thus 
with  the  Greek  measures  will  be  given  below,  and  may  be 
further  explained  by  stating  that  while  the  Attic  talent  of 
Solon  was  divided  into  60  minas,  the  same  weight  of  water 
contained  in  the  amphora  was  divided  into  80  pounds,  thus- 
making  3  Attic  minas  equal  to  4  Eoman  pounds.  Originally 
the  Roman  pound  was  established  on  the  basis  of  the  Aeginetan 
weight,  and  was  equal  to  T^  of  the  Aeginetan  half  mina, 
this  basis  being  used  in  the  Roman  coinage. 

As  a  measure  of  liquid  capacity  the  Romans  had  the  amphora, 
which  was  equal  to  a  cubic  foot  and  contained  80  librae  (pounds) 
of  water.  This  was  divided  into  8  congii,  each  composed  of 
6  sextarii  with  further  subdivisions.  For  dry  measure  one  third 
of  the  amphora  or  modius  served  as  the  unit,  and  was  made  up 
of  16  sextarii.  These  measures  harmonized  with  those  of  Greece,, 
inasmuch  as  the  amphora  was  two  thirds  of  the  Attic  metretes, 
and  the  modius  was  one  sixth  of  the  medimnos.  In  passing, 
mention  might  be  made  of  the  fact  that  a  foot  derived  theo- 
retically from  the  amphora  would  not  give  a  cube  equal  to 
the  amphora,  but  differing  by  as  much  as  a  twentieth  part 
and  in  some  cases  by  as  much  as  one  twelfth, ,  depending,  of 
course,  upon  the  cubical  contents  of  surviving  examples,  of  which 
there  are  several.1 

e  Roman  weights,  measures,  and  coinage,  by  virtue  of  the 
conquests  and  influence  of  the  empire,  found  their  way  all  over 
Western  Asia  and  Europe ;  and  with  the  decline  of  the  imperial 
power  formed  the  foundation  for  local  systems,  but  with  the  lack 
of  interest  in  science  which  soon  began  to  characterize  the  age 
and  the  general  decline  of  culture,  weights  and  measures  were  no 
longer  maintained  in  conformity  with  any  system  or  with  any 
due  regard  to  primary  standards.  Consequently  there  was  a 
distinct  corruption  of  measures,  and  until  the  revival  of  experi- 
mental science  in  the  middle  ages  but  little  attention  was 
paid  to  the  subject.  Indeed,  all  standards  and  systems  were 
practically  neglected,  and  by  the  sixteenth  century  there  was 
virtually  a  return  to  the  body  measures  throughout  Europe^/  """""' 

1  Flinders  Petrie,  article  "Weights  and  Measures,"  Encyclopaedia,  Britannica? 
9th  ed.  vol.  xxiv.  p.  486.  X_.X 


THE   SCIENCE   OF   METROLOGY  29 

\ j/ 

Previous  to   the   beginnings  of   European  scientific  investiga-  I/ 
tion1  there  was,  however,  important  work  done  by  the  Arabs,  and  v 
as  measurement  is  an  essential  of  all  experimental  science,  it  was 
natural   that  they  should   have  devoted  much  attention  to  the 

>ject,  and  included  the  discussion  of  measures  in  their  writings. 

is  quite  certain  that  the  measures  of  the  Arabs  owe  their 
rigin  to  the  old  Babylonian  measures,  especially  as  their 
philosophers  were  careful  students  of  antiquity ;  but  it  is  evident 
that  while  the  measures  were  maintained  they  lost  sight  of  the 
underlying  principles,  and  when  it  became  necessary  to  define 
them  or  refer  them  to  standards,  entirely  new  methods  were 
•employed.  In  these  an  attempt  was  made  to  secure  a  natural 
basis,  and  such  fundamental  units  as  a  degree  of  the  earth,  hairs 
of  horses  or  mules,  and  grains  of  barley  were  used.  Then,  too, 
the  contact  between  the  Arabs  and  the  Egyptians  had  its  effect, 
and  old  and  new  measures  were  blended  so  that  the  absolute 
value  of  the  weights  and  measures  is  quite  impossible  to 
determine,  though  by  references  ito^nnjejit  authorities  relative 
values  can  be  obtained  in  maiiv^-sase/2!  It  was  from  the  Arabs 
that  the  Yusdrurnaii  pound  of  CTiarlemagne,  for  so  many  years 
the  standard  of  France,  was  obtained,  and  the  idea  of  using 
barleycorns  for  the  measure  of  length,  as  was  done  subsequently 
in  England  by  statute. 

In  this  connection  mention  might  be  made  of  a  unit  of  length, 
namely,  the  "  black  cubit,"  which  figured  in  an  important  C- 
measurement  of  a  degree  of  the  earth's  surface  executed  in  830 
A.D.  by  the  astronomers  of  the  Caliph  Al-Mamun  (713-833). 
This  measurement,  made  on  the  plains  of  Mesopotamia,  is 
generally  spoken  of  in  connection  with  similar  measurements 
made  by  Eratosthenes  (c.  276 — c.  196  B.C.),  the  Alexandrian,  as 
they  were  the  forerunners  of  later  geodetic  work,  on  which  in 
part  the  modern  metric  system  was  founded,  it  being  of  course 
unnecessary  to  say  that  this  and  other  ancient  astronomers 
believed  in  the  spheroidal  form  of  the  earth.  i/T2je'"  ityack  cubit," 


1  About  the  earliest  systematic  works  in  Metrology  in  frpgTgju^Xre  A  Discourse 
en  the  Roman  Foot  and  Denarius  and  Origin  and  Antiquity  of  our  English  Weights 
and  Measures  (London,  1745),  by  John  Greaves  (1602-1652),  and  De  Memuris 
*t  Ponderibus  Antiquis  (Oxford,  1699),  by  Edward  Bernard  (1636-1696[7j). 

2  See  Boeckh,  Metrologische  Untersuchungen  (Berlin,  1838),  pp.  246  et  seq. 


30       EVOLUTION   OF   WEIGHTS   AND   MEASURES 

however  scientific  the  use  to  which  it  was  put,  was  not  due  to> 
any  particular  metrological  study,  but,  according  to  tradition,  was 
the  length  of  the  arm  of  a  favorite  black  slave  of  the  Caliph,  and 
has  been  said  by  Jomard  to  have  been  equal  to  519*16  mm.1 

The  source  from  which  the  Anglo-Saxons  derived  their  weights 
and  measures  is  not  particularly  certain,  yet  they  early  en- 
deavoured to  secure  uniformity  by  enacting  good  laws,2  and  in 
this  they  were  so  successful  that  they  were  enabled  to  maintain 
these  weights  and  measures  in  their  integrity  despite  the  Norman 
conquest.3  In  fact,  they  were  specially  recognized  and  preserved 
by  .a  decree  of  William  the  Conqueror,!  which  stated  that  "  the 
measures  and  weights  shall  .be  true  and  stamped  in  all  parts  of 
the  country,  as  had  before  been  ordained  by  law."  The  stan- 
dards of  the  Saxon  kings  which  had  been  preserved  at  Winchester 
were,  however,  removed  to  London,  where  they  were  deposited  in 
the  crypt  chapel  of  Edward  the  Confessor  in  Westminster  Abbey, 
which  later  became  known  as  the  Pyx  Chapel,  as  here  were  also- 
preserved  the  standard  trial  plates  for  gold  and  silver  coin  used 
at  the  trials  of  the  pyx,  or  formal  official  assay  of  the  coin  of  the 
realm.4  With  Winchester  are  associated  the  earliest  Anglo- 
Saxon  weights  and  measures,  and  their  authority  as  standards- 
is  said  to  date  back  to  King  Edgar  (reigned  958-975)^  who  decreed 
that  "  the  measures  of  Winchester  shall  be  the  standard."  The 
unit  of  length  was  the  yard  or  gird,  which  was  identical  with  the 

1  See  Boeckh,  Metrologische  Untersuchungen  (Berlin,  1838),  pp.  246,  250-3. 

2  Greaves,  Origin  and  Antiquity  of  our  English   Weights  and  Measures  (London, 
1745),  p.  68. 

3 Bishop  Fleetwood's  Chronicon  Preciosum  (London,  1745),  p.  27:  "It  was  a 
good  law  of  King  Edgar  that  there  should  be  the  satne  money,  the  same  weight, 
and  the  same  measures,  throughout  the  kingdom,  but  it  was  never  well  observed. 
What  can  be  more  vexatious  and  unprofitable  both  to  men  of  reading  and  practice, 
than  to  find  that  when  they  go  out  of  one  country  into  another,  they  must  learn 
a  new  language  or  cannot  buy  or  sell  anything.  An  acre  is  not  an  acre  ;  nor  a 
bushel  a  bushel  if  you  but  travel  ten  miles.  A  pound  is  not  a  pound  if  you  go 
from  a  goldsmith  to  a  grocer,  nor  a  gallon  a  gallon  if  you  go  from  the  alehouse  ta 
the  tavern.  What  purpose  does  this  variety  serve,  or  what  necessity  is  there, 
which  the  difference  of  price  would  not  better  answer  and  supply?" 

4  See  H.  J.  Chancy,  Our  Weights  and  Measures  (London,  1897),  pp.  120-121. 
An  interesting  account  of  the  Pyx  Chamber  together  with  a  description  of  the 
Jewel  Tower,  now  the  Office  of  the  Standards,  will  be  found  in  "The  Story  of  a 
Tower,'?  The  Art  Journal  (London,  1900),  pp.  200-203  and  244-247. 


THE   SCIENCE   OF   METROLOGY 

ell,  and  as  late  as  the  reign  of  Richard  II.  (1377-1399)  the  words 
wrga  or  verge  (yard)  and  ulna  or  aulne  (ell)  are  found  in  the  laws, 
and  official  documents  in  Latin  or  Norman  French,  as  the  case 
may  be,  to  denote  the  same  unit  of  length.  In  addition  to  the- 
purely  Saxon  measures  there  were  those  which  had  been  brought 
by  the  Roman,  and  which,  though  incommensurable  with  Saxon 
measures,  had  survived  and  become  assimilated  with  the  older 
measures.  Among  these  were  the  mile,  corresponding  to  the 
Roman  millia  passuum,  the  inch  and  the  foot,  which  soon  became 
recognized  as  purely  English  measiires  and  to  have  their  own 
fixed  values.  Then,  in  addition,  when  the  Belgic  tribes  migrated 
to  Britain,  they  brought  the  Belgic  foot  of  the  Tungri,  which 
was  ^  longer  than  the  Roman  foot,  and  was  used  until  the 
fifteenth  century.1  The  average  length  of  this  foot  was  13*22 
inches,  and  a  yard  formed  by  three  such  feet  would  be  39*66 
inches,  which  would  correspond  most  closely  with  the  meter  of 
to-day,  which  is  equivalent  to  39*37  inches.  Such  a  yard  existed 
and  was  known  as  the  yard  and  the  full  hand,  and  eventually 
was  suppressed  by  law  in  1439.  This  was  extremely  unfortunate,, 
as  had  this  yard  been  retained  it  would  have  ensured  a  corre- 
spondence with  the  French  metric  system  without  the  slightest 
difficulty.  Furthermore,  we  are  informed  that  the  old  English 
system  was  largely  decimal,  and  had  these  features  been  pre- 
served a  vast  improvement  would  have  been  worked  in  the 
wretched  system,  or  lack  of  system,  with  which  the  English* 
speaking  people  have  been  afflicted  for  centuries. 

In  the  Domesday  Book  (1086)  we  find  the  Saxon  yard  used  as 
a  unit  of  measure,  and  land  thus  measured  is  referred  to  as  terra 
virgata,  and  shortly  afterwards,  from  the  reign  of  Henry  I. 
(reigned  1100-1135),  the  tradition  is  current  that  the  legal  yard 
was  established  from  the  length  of  that  monarch's  arm.  In  the 
reign  of  Richard  I.  (reigned  1189-1199)  there  were  laws  enacted 
providing  for  standards  of  length  constructed  of  iron  and  for 
measures  of  capacity  whose  brims  should  be  of  this  material  also, 
suitable  standard  measures  to  be  kept  by  sheriffs  and  magistrates.* 

blinders  Petrie,  article  "Weights  and  Measures,"  Encyclopaedia  Brilannica, 
9th  ed.  vol.  xxiv.  p.  484. 

2  See  Kelly,  Metrology  (London,  1816),  p.  336.  A  brief  and  interesting  account 
of  early  history  of  British  Weights  and  Measures,  with  summary  of  legislation. 


A  ' 

32       EVOLUTION   OF   WEIGHTS   AND   MEASURES 

The  most  important  early  English  legislation  was  contained  in 
Magna  Charta  (1215),  and  laid  stress  on  the  principle  of  uni- 
formity ^by  providing  that  there  should  be  throughout  the  realm, 
•one  measure  of  wine,  one  of  ale,  and  one  of  corn,  viz.,  the  quarter 
of  London :  and  that  it  should  be  of  weights  as  of  measures. 
This  declaration  of  uniformity  was  considered  so  fundamental  that 
it  was  subsequently  repeated  in  numerous  statutes  in  essentially 
its  original  form,  and  we  find  many  acts  passed  as  occasion 
demanded  to  carry  out  its  manifest  intention.  This  naturally 
involved  the  definition  of  the  standards  and  measures,  and  from 
time  to  time  statutes  are  found  which  supply  us  with  more  or 
less  complete  information  about  the  measures  of  the  period. 
Thus,  while  we  know  that  the  unit  of  monetary  weight  was  a  pound 
used  from  the  times  of  the  Saxon  kings,  yet  we  do  not  find  it 
•defined  until  the  time  of  Henry  III.  (51  Henry  III.,  stat.  I.  1266), 
when  the  relation  of  the  various  weights  and  measures  are  given 
by  the  following  law,  forming  a  part  of  the  well  known  statute  of 
the  Assize  of  Bread  and  Ale,  where  it  is  stated,  "  that  by  the 
consent  of  the  whole  realm  of  England,  the  measure  of  our  Lord 
the  king  was  made,  viz.,  an  English  penny  called  a  sterling,  round 
and  without  any  clipping,  shall  weigh  thirty-two  wheatcorns  in 
the  midst  of  the  ear ; 1  and  twenty  pence  do  make  an  ounce,  and 
twelve  ounces  a  pound :  and  eight  pounds  do  make  a  gallon  of 
wine,  and  eight  gallons  of  wine  do  make  a  bushel,  which  is  the 
eighth  part  of  a  quarter."  Thus  we  have  defined  the  ancient 
Tower  Pound,  which,  having  the  same  weight  as  the  old  German 
medicinal  or  apothecaries  pound,  is  believed  to  have  been  derived 
from  the  mina  of  Ptolemy  or  one-sixtieth  part  of  the  Lesser 
Alexandrian  Talent  of  silver,  as  it  was  but  63  grains  lighter  than 
that  weight.  This  was  the  earliest  form  of  the  British  sterling 
pound,  and  the  division  into  20  shillings  of  12  pence  each  was 
the  same  as  is  now  practised,  and  in  fact  was  the  same  as  the 
division  of  the  lime  esterlin  of  Charlemagne,  which  was  slightly 
heavier  (5666  Troy  grains  as  compared  with  5400,  see  p.  38). 
In  addition,  the  English  monetary  weights  were  connected  with 
those  of  Germany,  based  on  the  Cologne  mark,  by  a  mint  weight 

1 "  This  pennyweight  was  equal  to  22^  Troy  grains,  which  is  found  to  be  the 
average  weight  of  existing  coined  silver  pennies  of  the  Saxon  Norman  Kings  " 
.(Chisholm,  Weighing  and  Measuring,  London,  1877). 


THE   SCIENCE   OF   METROLOGY  33 

substantially  equivalent  to  the  latter  and  equal  to  two-thirds  of 
the  Tower  pound.  This  was  known  as  a  mark,  and  was  used  for 
denoting  both  the  weight  and  value  of  silver  under  the  Norman 
kings.1  While  the  Tower  pound  was  defined  in  terms  of  grains 
of  wheat,  nevertheless  it  did  not  originally  depend  upon  them, 
and  their  inclusion  in  the  English  system  of  weights  was  doubt- 
less due  to  French  influences  subsequent  to  the  Norman  Conquest, 
as  the  French  had  doubtless  derived  this  idea  from  Oriental 
sources.  With  the  Tower  pound  used  for  mint  purposes,  and  for 
the  derivation  of  measures  of  capacity,  as  well  as  for  precious 
metals  in  general  and  drugs,  there  must  be  considered  the  com- 
mercial pound  (libra  mercatoria),  which  is  of  almost  as  great 
antiquity  and  of  far  mone  general  use.  It  also  is  defined  in  a 
statute  of  Henry  III.  (54  Henry  III.)  and  was  the  weight  of  25 
shillings,  or  in  other  words  equivalent  to  15  ounces  of  the  Tower 
pound.  Commercial  pounds  were  used  also  on  the  continent 
of  Europe  along  with  the  Troy  pound,  and  it  is  to  one  of 
these,  namely  the  French  commercial  pound  of  16  ounces,  that 
we  have  to  look  for  the  source  of  the  English  avoirdupois 
pound  which  soon  supplanted  the  commercial  pound  in  that 
country. 

The  early  English  Tower  and  commercial  pounds  were  forced 
to  give  way  before  the  French  weights,  the  Troy  .pound  and  the 
avoirdupois  pound,  whose  use  the  more  intimate  contact  following 
the  English  victories  in  France  at  Poitiers  and  on  other  fields  had 
doubtless  spread  through  the  English  realm.  As  to  the  source  of 
the  Troy  pound  there  is  a  difference  of  authorities,  but  it  is  usual 
to  credit  it  to  the  city  of  Troyes  in  France,  and  in  support  of  this 
view  it  is  stated  that  associated  with  this  city,  a  town  of  some 
commercial  importance,  were  a  lime  de  Troyes  and  a  marc  de  Troyes, 
whose  weights  were  comparable  with  the  modern  Troy  pound. 
'Going  back  still  further,  it  is  possible  to  derive  the  Troy  pound 
from  the  Eoman  weight  of  5759'2  grains,  which  was  the  y^  of 
the  large  Alexandrian  talent.  This  weight,  after  the  fashion  of 
the  Romans,  was  divided  into  12  ounces,  and  the  original  unit 
and  its  division  may  possibly  have  survived.  At  all  events  the 
Troy  pound  slowly  made  its  way  in  England,  and  from  as  early 
as  the  first  year  of  the  reign  of  Henry  IV.,  when  it  was  employed 

1H.  W.  Chisholm,  The  Art  of  Weighing  and  Measuring  (London,  1877),  p.  55. 

C 


34       EVOLUTION   OF   WEIGHTS   AND   MEASURES 

in  an  inventory  of  the  Royal  plate,  it  was  increasingly  used.  In 
1495,  in  denning  the  bushel  and  the  gallon,  Henry  VII.  made  use 
of  the  Troy  pound,  and  in  1527  the  Tower  pound  was  formally 
abolished  as  the  legal  standard  at  the  Mint  by  an  Ordinance 
(18  Henry  VIII.)  enacting  that  "  the  Pounde  Towre  shall  be  no 
more  used  and  occupied,  but  al  maner  of  golde  and  sylver  shall 
be  wayed  by  the  Pounde  Troye,  which  maketh  xii  oz.  Troye, 
which  excedith  the  Pounde  Towre  in  weight  iii  quarters  of  the 
oz."  Likewise,  as  we  have  indicated,  the  avoirdupois  pound  was 
adopted  as  a  commercial  pound,  and  formed  of  16  avoirdupois 
ounces,  and  composed  of  7000  Troy  grains,  it  is  mentioned  in 
a  statute  (Tractatus  Ponderibus  et  Mensuris)  of  Edward  I. 
(31  Edward  I.  1303).  From  these  origins  the  English  Troy  and 
avoirdupois  pound  have  descended  in  substantial  integrity  to  the 
present  time,  and  such  changes  as  have  been  made  have  been  due 
to  the  restoration  of  standards,  and  have  been  of  a  minute  and 
unavoidable  character. 

Many  standards  of  weight  were  constructed  based  on  these 
fundamental  definitions,  and  a  number  of  them  are  still  in  exist- 
ence, having  been  used  on  numerous  occasions  for  deriving  other 
standards.  In  fact,  one  bell-shaped  avoirdupois  pound  of  the 
Exchequer  of  the  reign  of  Queen  Elizabeth  was  continuously  used 
for  this  purpose  from  1588  to  1825.  This  weight,  which  at  the 
time  of  its  construction  in  1588  was  supposed  to  be  equal  to  7002 
Troy  grains,  was  found  in  1873  to  weigh  6999  grains  of  the 
imperial  standard  pound.1 

In  1758  a  standard  Troy  pound  was  constructed  and  standard- 
ized by  Harris  under  authorization  of  an  Act  of  Parliament,  but 
it  was  not  legalized  until  1824  (5  Geo.  IV.  c.  74).  It  was  then 
specified  (§  5)  that  in  the  event  of  the  loss  or  destruction  of  this 
standard,  that  it  should  be  reconstructed  by  considering  that  a 
cubic  inch  of  distilled  water  at  62  degrees  Fahrenheit,  weighed  in 
air  with  brass  weights,  and  at  30  inches  pressure  of  the  mercurial 
barometer,  should  weigh  252*458  grains,  of  which  the  Troy  pound 
contained  57 60.2  This  standard  was  destroyed  together  with 

1H.  W.  Chisholm,  The  Art  of  Weighing  and  Measuring  (London,  1877),  pp.  62 
and  63. 

2  This  definition  bound  the  unit  of  weight  to  the  unit  of  length,  which  was  then 
considered  fixed  by  its  reference  to  the  second's  pendulum. 


THE   SCIENCE   OF   METROLOGY  35 

the  standard  yard  by  the  fire  of  October  16,  1834,  when  the 
Houses  of  Parliament  were  burnt.  To  construct  new  standards  a 
Standards  Commission  was  appointed  in  1843,  and  for  the  unit  of 
weight  the  avoirdupois  pound  was  taken  as  the  basis.  The  new 
standard  was  defined  in  terms  of  the  lost  Troy  pound  as  given  by 
various  existing  standards,  and  was  duly  legalized  in  1855  (18  and 
19  Viet.  c.  72).  This  standard  pound  will  be  more  specifically 
described  when  we  come  to  discuss  the  subject  of  Standards  in  a 
subsequent  chapter.1 

From  the  definition  of  the  measures  of  capacity,  given  in  the  "\ 
Statute  of  the  Assize  of  Bread  and  Ale  referred  to  above,  the    \ 
gallon  and  the  bushel  were  obtained  from  the  pound,  usmg^wine     I 
as  the  measuring  medium.     This  class  of  measures  was  one  that  j 
greatly  concerned  the  government  on  account  of  the  collection  of 
the  excise  duties,  and   there  are  numerous  statutes  defining  or 
regulating  in  one  way  or  another  the  capacity  and  use  of  these 
measures.      On  the  basis  of  the  early  legal  definition,  however, 
Henry  VII.  caused  to  be  constructed  a  standard  corn  gallon  and 
a   standard  corn  bushel,  the  former  having  a  capacity  of  27  4 J 
cubic  inches  and  the  latter  2150J  cubic  inches.     These  standards 
date   from    1495,  and   are   now  in  actual  existence.     The  Win- 
chester  corn  gallon,  as  the   measure   is    known,   was   employed 
until  it  was  supplanted  in  1824  by  the  imperial  gallon,  while  its 
companion,  the  Winchester  bushel,  which  was  similarly  outlawed 
in  1824  in  favour  of  the  imperial  bushel  in   Great  Britain,  has 
survived  in  the  United  States.      In  1601  we  find  the  British  ale 
gallon  with   a  capacity  of  282  cubic  inches  duly  recognized  by 
Queen  Elizabeth,   and  there  is    extant    an   Exchequer  standard 
quart  which  bears  this  date  and  the  royal  initials  and  crown. 

In  the  reign  of  Queen  Anne  the  standard  wine  gallon  was 
defined  by 'statute  (5  Ann.  cap.  27,  17)  as  "any  cylinder  7  inches  ]A/ 
in  diameter,  and  6  inches  deep,  or  any  vessel  containing  231 
cubical  inches  and  no  more  shall  be  a  lawful  wine  gallon." 
Such  a  standard  of  the  Exchequer  dated  1707  is  still  extant.  On 
the  reorganization  of  the  weights  and  measures  in  1824  the  wine 
gallon  was  abolished,  but  it  was  never  supplanted  in  the  United 

1  Chas.  Ed.  Guillaume,  Unites  et  Etalons  (Paris,  1893),  p.  96.  H.  W.  Chisholm, 
The  Art  of  Weighing  and  Measuring  (London,  1877),  pp.  69-81.  W.  H.  Miller, 
Philosophical  Transactions  (London,  1856),  part  iii. 


36       EVOLUTION   OF   WEIGHTS   AND   MEASURES 

States,  and  remains  as  the  legal  gallon.  The  British  imperial 
gallon,  legalized  in  1824  (5  Geo.  IV.  c.  74)  to  the  exclusion  of  the 
three  former  gallon  measures,  and  which  forms  the  basis  of  the 
present  British  measures  of  capacity,  instead  of  being  based  on  a 
given  number  of  cubic  inches,  was  taken  as  the  volume  of  ten 
pounds  of  pure  distilled  water  at  62  degrees  Fahrenheit.  This 
corresponds  to  277*274  cubic  inches.  With  the  gallon  as  the 
unit  of  capacity  for  liquid  measures,  it  was  determined  to  derive 
the  imperial  standard  bushel  or  unit  of  capacity  by  taking  a 
volume  equal  to  eight  imperial  gallons,  or  a  volume  corresponding 
to  2218*192  cubic  inches. 

Unlike  the  measures  of  weight  and  capacity,  there  have  been 
few  changes  in  those  of  length  from  the  times  of  the  Saxons,  and 
the  earliest  surviving  standards  of  length,  those  of  Henry  VII. 
(about  1490),  and  Elizabeth  (about  1588),  vary  scarcely  more 
than  a  hundredth  of  an  inch  from  the  present  imperial  yard.1 
With  the  second  of  these  standards  there  is  also  an  ell  rod  of 
45  inches,  and  a  bar  with  a  bed  or  matrix  for  both  the  yard  and 
the  ell  rods,  but  such  an  ell,  which  doubtless  corresponded  to  the 
French  measure  of  cloth,  does  not  appear  in  any  statute  or  in 
the  records  of  the  standards  of  this  time.  In  fact,  we  find  the 
Anglo-Saxon  measures  of  length  perpetuated  on  the  same  basis 
as  is  given  in  the  statute  of  Edward  II.  (17  Edward  II.  1324), 
where  there  is  a  restatement  in  statutory  form  of  what  has  since 
become  the  well-known  rule  that  three  barley-corns,  round  and 
dry,  make  an  inch,  twelve  inches  a  foot,  three  feet  a  yard  (ulna), 
five  and  a  half  yards  a  perch,  and  forty  perches  in  length  and 
four  in  breadth  an  acre.2 

Consequently  the  general  discussion  that  has  been  devoted  to 

1  See  chapter  x.  on  Standards,  pp.  243-244. 

2  See  H.  W.  Chisholm,  Seventh  Annual  Report  of  the  Warden  of  the  Standards, 
1872-3  (London),  pp.  25  and  34,  English  Parliamentary  Papers,  Reports  from 
Commissioners,    1873,    vol.    xxxviii.      Id.,     Weighing   and    Measuring    (London, 
1877),  pp.  51-53.     George  Graham,  "Description  of  Standards  and  Use  of  Beam 
Compasses,"  Philosophical  Transactions  (London,  1742-3),  vol.  xlii.  pp.  541-556. 
Francis    Baily,    Memoirs    Royal  Astronomical  Society  (London),  vol.    ix.    1836, 
pp.  35-184.     William  Harkness,  "The  Progress  of  Science  as  Exemplified  in  the 
Art  of   Weighing    and    Measuring,"    vol.    x.    Bulletin   Philosophical  Society   of 
Washington,    D.C.,   published    as  vol.    xxx.    Smithsonian   Miscellaneous   Collec- 
tions.    The  latter  contains  a  good  resume"  of  British  weights  and  measures  as 
well  as  a  useful  bibliography. 


THE   SCIENCE   OF  METROLOGY  37 

the  British  measures  of  length  has  been  mainly  towards  securing 
standards  of  greater  accuracy,  or  with  the  object  of  obtaining 
either  a  decimal  division  or  the  adoption  of  the  metric  system. 
With  the  exception  of  the  act  of  1824,  which  defined  the  yard  in 
terms  of  the  second's  pendulum,  and  provided  in  case  of  its  loss 
or  destruction  that  it  should  be  replaced  on  that  basis,  little 
has  been  done  in  the  way  of  legislative  enactment  save  to 
recognize  and  establish  legally  new  standards  of  length.  The 
determination  and  construction  of  such  standards,  however,  has 
been  of  extreme  importance,  and  has  involved  most  careful  and 
accurate  scientific  work,  so  that  for  this  reason  the  various  British 
standards  and  their  development  can  best  be  treated  in  that 
portion  of  the  present  volume  devoted  to  this  subject.1 

While  there  have  been  for  well  over  a  century  many  and 
earnest  advocates  of  a  decimal  division  of  British  weights 
and  currency,  yet  the  net  results  of  their  labors  and  agitation 
have  been  practically  nothing  other  than  to  strengthen  the 
cause  of  the  metric  partisans.  In  fact,  decimalization  never 
has  progressed  to  the  same  point  as  in  the  United  States,  and 
it  is  probable  that  the  old  weights,  measures,  and  methods 
will  remain  until  supplanted  by  the  metric  system.2 

Although  the  preservation  of  the  French  standards  of  measure 
in  the  royal  palace  is  recorded  from  the  time  of  Dagobert  (650),3 
yet  it  is  usual  to  trace  back  such  measures  as  might  properly 
be  considered  as  forming  the  national  system  to  the  time  of 
Charlemagne  (768-814),  since  during  his  reign  there  was  a 
uniformity  of  weights  and  measures,  and  reproductions  of  the 
royal  standards  were  widely  distributed  over  the  realm.4  The 
unit  of  length  in  this  system  was  the  pied  de  Hoi,  or  royal 
foot,  representing,  according  to  tradition,  the  length  of  the 
foot  of  the  monarch,  and  which,  following  the  duodecimal 

1  See  chapter  x. — Standards  and  Comparison. 

2  For  progress  of  Metric  System  in  Great  Britain,  see  chapter  iii.  pp.  98  et  seq. 
It  is  of  course  impossible  in  the  present  space  to  describe  the  various  measures 
of  Scotland,  Ireland,  and  other  local  systems.     These  will  be  found  quite  fully 
described  in  Kelly,  Metrology  (London,  1816),  and  also  in  Chaney,  Our  Weights 
and  Measures  (London,    1897),   the  latter  containing  also  a  description   of   the 
various  standards. 

3Paucton,  Metrologie  ou  Traite  dts  Mesures,  Poids  et  Monnoies  (Paris,  1780),  p.  8. 
4  Ibid.  p.  13. 


J 


38       EVOLUTION   OF   WEIGHTS   AND   MEASURES 

division  derived  from  the  Eomans,  was  divided  into  12  inches 
(pouce)  of  12  lines,  which  in  turn  were  composed  of  12  points. 
The  French  foot  was  longer  than  the  English  foot,  being  equal 
to  12*79  inches  of  the  latter,  and  considerably  longer  than  the 
ancient  Roman  foot,  which  was  11 '65  English  inches  in  length. 
In  the  French  system  there  was  also  the  toise  or  fathom  of  six 
feet,  and  the  earliest  record  of  a  standard  of  length  dates  back  to 
the  Toise  du  Grand  Chatelet,  constructed  in  1668,  and  based  (though 
five  lignes  shorter)  on  the  ancient  toise  de  masons  of  Paris,  which 
was  doubtless  as  old  as  the  times  of  Charlemagne.1  It  is  said 
by  La  Condamine2  to  represent  one  half  the  distance  (12  feet) 
between  the  walls  of  the  inner  gate  of  the  Louvre.  Subsequently, 
copies  of  this  were  made,  and  the  toise  was  used  as  the  basis  for 
standards  of  linear  measures,  such  as  the  Toise  de  Perou?  There 
was  also  the  aune  or  ell,  which,  originally  a  double  cubit,  became 
adopted  as  a  unit  of  linear  measure  for  cloth,  and  survived  until 
displaced  by  the  meter.  A  standard  Aune  des  Marchands, 
Merciers  et  Grossiers,  1554,  divided  into  halves,  quarters,  thirds, 
sixths,  etc.,  was  preserved  by  that  guild,  and  was  the  basis  of 
this  unit.  The  aune  of  Paris  corresponded  to  46^-J  Eng.  inches, 
but  it  was  never  adopted  in  the  latter  country  to  any  considerable 
extent  or  authorized  by  law,  though  a  cloth  aune  or  ell  of  45  in. 
isj^dnd  marked  on  the  standard  yard  of  Queen  Elizabeth.4 

r  the  origin  of  standards  of  weight  in  France  we  have  to  go 
to  the  Arabs,  as  the  basis  of  the  ancient  French  system  is  re- 
futed to  be  an  Arab  yusdruma,  which  was  sent  by  Caliph  Al  Mamun 
(786-833)  to  Charlemagne.  This  yusdruma,  or  later  Arab  pound, 
was  the  monetary  pound  or  lime  esterlin  of  Charlemagne,  and 
amounted  to  5666  J  grains,  or  367'1 28  grams.6  It  was  divided  into 
12  ounces,  or  20  sols,  of  12  deniers,  of  2  oboles  of  12  grains,  or 
5760  grains  in  the  aggregate,  each  grain  weighing  '063738  grams. 

1  La  Hire,  Mem.  de  VAcad.  Roy.  des  Sciences,  1714,  pp.  394-400  (Paris,  1717). 
2 La  Condamine,    Mdmoires   de  I'Acad.    Hoy.    des   Sciences,    1772,   2nd    part, 
pp.  482-501  (Paris,  1776). 

3  See  chapter  x.  on  Standards. 

4  See  chapter  on  Standards,  p.  243.     Also  ante,  p.  31. 

5 The  name  "esterlin"  was  employed  at  one  time  in  the  French  language  to 
signify  "true,"  being  equivalent  to  the  modern  Fr.  word  "veritable."  It  has, 
however,  disappeared  from  use,  but  has  been  retained  in  English,  with  the  same 
.signification,  in  the  form  of  "sterling,"  as,  for  example,  "pounds  sterling." 


THE   SCIENCE   OF   METROLOGY  39 

The  livre  esterlin  of  Charlemagne  was  one  and  a  half  times  the 
weight  of  the  marc  of  the  monetary  system  which  was  established 
between  1076  and  1093  by  Philip  I.,  who  used  8  of  the  12  ounces 
.  of  the  former  system  for  this  purpose.  This  marc  was  doubled, 
and  made  to  consist  of  16  ounces,  by  King  John  the  Good,  in 
1350,  and  it  was  adjusted  according  to  the  weights  of  Charlemagne. 
The  weights  of  King  John  were  known  as  the  "  pile  de  Charle- 
magne," and  were  the  French  standards  of  weight  until  the 
adoption  of  the  Metric  System  in  1789.1  In  this  system  the 
livre  poid  de  marc,  or  pound,  consisted  of  two  marcs  or  half- 
pounds,  4  quarterons,  8  half-quarterons,  16  ounces,  32  half-ounces, 
128  gros  (drachme)  or  grams,  384  scruples,  or  deniers,  9216  grains. 
There  were  also  in  France  four  other  marcs  duly  and  legally 
recognized,  viz.,  that  of  Kochelle,  which  was  called  English,  equal 
to  1 3  sols,  4  deniers,  in  terms  of  the  livre  esterlin ;  that  of 
Limoges,  equivalent  to  13  sols,  3  oboles ;  that  o£  Tours,  equal  to 
12  sols,  11  deniers,  1  obole ;  and  that  of  Troyes  and  Paris,  equi- 
valent to  14  sols,  2  deniers.2 

We  have  referred  specifically  to  early  measures  only  in  Great 
Britain  and  France,  as  throughout  the  rest  of  Europe  there  was 
such  great  diversity  until  well  into  the  nineteenth  century  that 
little  would  be  gained  for  our  purpose  by  considering  the  dozens 
of  kingdoms,  principalities,  free  cities,  etc.,  each  with  their 
separate  systems.  Local  conditions  and  traditions  everywhere 
governed,  and  not  only  in  different  countries  in  the  same  region 
would  there  be  different  values  for  the  same  weights  and 
measures,  but  also  in  different  towns  of  the  same  state.3  While 
the  names  feet,  pounds,  etc.,  were  quite  universally  employed,  yet 
they  designated  different  quantities,  and  save  for  arbitrary 
standards,  possibly  in  many  cases  not  even  duly  legalized,  there 
was  no  attempt  at  securing  uniformity.  A  foot  might  be  divided 


1  Guillaume,  p.  94,  Lex  Unites  et  Etalons  (Paris, 

2  Quoted  by  Guillaume,  p.  95,  Les  Unite's  et  Etalons,  from  Chronique  de  1329 
•environ. 

3  "At  the  close   of  the    last   (eighteenth)   century,  in  different  parts  of  the 
world,  the  word  pound  was   applied  to  391   different  units  of  weight  and  the 
word  foot  to  282  different  units  of  length."     T.  C.  Mendenhall,  Measurements  of 
Precision.      Such  a   list  with  British  and  metric  equivalents  may  be  found  in 
Barnard,    The  Metric  System  (Boston,    1879),    pp.    348-360.     The   kilogram   has 
.superseded  over  370  of  the  different  pounds. 


40       EVOLUTION   OF   WEIGHTS   AND   MEASURES 

duodecimally,  as  was  done  by  the  Romans,  or,  on  the  other  hand, 
it  might  be  divided  into  nine,  ten,  eleven,  or  thirteen  inches. 
Then  again  the  actual  distance  represented  by  a  foot  varied 
from  9  to  18  inches,  and  equivalents  are  now  known  for  many 
different  European  feet. 

As  to  the  sources  of  these  measures,  we  have  to  look  to  the 
Romans  and  to  the  East,  as  the  former  nation  in  its  conquests 
overran  a  great  part  of  Europe,  and  implanted  its  weights  and 
measures  with  more  or  less  permanence,  while  the  effects  of  trade 
with  the  Orient  and  the  intellectual  influence  of  the  Arabs 
doubtless  served  to  introduce  new  measures  or  to  corrupt  old 
ones.  Several  mark  weights  soon  became  known  as  standards 
for  coinage  and  precious  metals,  notably  that  at  Cologne,  while  the 
Rhine  foot  enjoyed  a  pre-eminence  in  the  neighboring  countries.1 
As  practically  no  scientific  work  of  a  quantitative  character  was 
done  for  many  centuries,  the  influence  of  science  in  systematizing 
and  demanding  exact  standards  of  measure  was  not  felt,  so  that 
only  the  needs  of  trade,  often  of  a  most  restricted  character, 
which  could  be  satisfied  by  crude  and  imperfect  systems,  had 
to  be  provided  for.  The  lineage  of  many  of  the  old  European 
weights  and  measures  has  been  traced  more  or  less  satisfactorily 
back  to  ancient  times,  but  the  subject  presents  little  scientific 
attraction,  save  to  the  historian  or  archaeologist  and  the  student 
of  metrology.2  Lack  of  system  prevailed,  and  apparently  was 
quite  satisfactory,  but  gradually  the  minds  of  scientists  and 
statesmen  became  aroused  to  the  importance  of  the  subject  and 
the  need  of  fundamental  changes,  and  a  rational  systematization 
was  urged,  which  found  its  first  substantial  fruit  in  the  develop- 
ment in  France  of  the  metric  system. 

1This  Rhine  foot  defined  in  Prussia  by  law  in  1816  was  standardized  by  Bessel 
in  1835-1838,  and  survived  in  that  kingdom  until  the  adoption  of  the  metric 
system.  It  is  still  (1906)  the  standard  of  length  in  Denmark. 

2  An  interesting  summary  of  ancient  and  modern  measures,  which,  however, 
must  be  modified  in  many  aspects,  and  considered  in  the  light  of  modern 
researches  and  theories,  is  contained  with  a  wealth  of  bibliographical  material 
in  Karsten,  Allgemeine  EncyHopadie  der  Physik,  vol  i.  "  Maass  und  Messen '" 
(Leipsic,  1869). 


CHAPTEE  II. 
ORIGIN  AND  DEVELOPMENT  OF  THE   METRIC   SYSTEM.1 

WHILE  the  inconveniences  and  difficulties  attending  arbitrary 
systems  of  weights  and  measures  were  appreciated,  nevertheless 
philosopher  and  peasant  alike  submitted,  and  it  took  many  years 
for  a  feeling  in  favour  of  a  rational  and  fixed  system  to  develop. 
Such  a  system  at  its  best,  as  we  have  seen,  would  involve  an 
invariable  unit  derived  from  nature  itself,  which  not  only  could 
be  reproduced  readily,  but  was  capable  of  being  measured  with  a 

JIn  this  chapter  detailed  references  have  been  given  to  authorities  for 
particular  statements  for  the  benefit  of  those  who  desire  to  pursue  the  subject 
further.  The  history  of  the  Metric  System  has  been  well  summed  up  in  a 
treatise  by  M.  Bigourdan  (Le  Systeme  Mdtrique,  Paris,  1901),  in  which  will  be 
found  usually  the  text  of  all  French  legislation  and  the  salient  features  of 
discussion  by  lawmakers  and  scientists,  as  well  as  a  complete  bibliography. 
There  is  also  an  excellent  historical  sketch,  "Notice  historique  sur  le  Systeme 
Metrique,  sur  ses  developpements  et  sur  sa  propagation,"  contained  in  the 
Annales  du  Conservatoire  (Imperial)  <les  Arts  et  Metier*,  by  General  A.  Morin 
(Paris,  1870),  vol.  ix.  pp.  573-640.  This  is  a  brief  but  excellent  description  of 
the  origin  and  development  of  the  system  by  a  member  of  the  Committee  of 
Verification,  director  of  the  Conservatoire  des  Arts  et  Metiers,  and  a  member 
of  the  first  International  Commission.  "A  Historical  Sketch  of  the  Foundation 
of  the  Metric  System,"  by  Ge'ne'ral  Bassot,  was  published  in  the  Annuaire  pour 
Van  1901,  of  the  Bureau  of  Longitude,  Paris  (translated  into  English  by  Miss 
F.  E.  Harpham  of  the  Astronomical  Department  of  Columbia  University,  and 
published  in  the  School  of  Mines  Quarterly,  vol.  xxiii.  No.  1,  November,  1901. 
First  and  foremost,  however,  is  the  classical  work  of  Me"chain  and  Delambre, 
Base  du  Systdme,  Me'trique,  3  vols.  (Paris,  1806-1810),  which  is  the  primary 
source  of  information  for  the  early  work  in  establishing  the  Metric  System.  It 
is,  of  course,  unnecessary  to  say  that  in  the  following  pages  these  works  have 
been  most  freely  used,  and  can  be  recommended  for  those  desiring  additional 
information  on  the  subject. 


42       EVOLUTION   OF   WEIGHTS   AND   MEASURES 

high  degree  of  precision.  Obviously  such  standards  as  barley- 
corns and  human  feet  did  not  possess  the  slightest  claim  to 
invariability,  and  as  soon  as  the  subject  began  to  be  considered 
seriously  and  earnestly  by  scientific  men,  the  choice  for  the 
fundamental  unit  of  linear  distance  became  narrowed  to  two 
classes  of  lengths,  and  around  them  most  of  the  subsequent 
discussion  centred.  One  was  the  length  of  a  fraction  of  a  great 
circle  of  the  earth,  while  the  other  was  the  length  or  a  fraction 
of  the  length  of  a  pendulum,  vibrating  in  intervals  of  one  second 
or  some  other  chosen  unit  of  time.  For  the  first,  proceeding  on 
the  assumption  that  the  earth  was  a  spheroid  (or  very  nearly  so), 
it  was  possible  to  measure  the  arc  of  a  great  circle  even  in  the 
seventeenth  century  without  any  great  difficulty.  Such  a  measure- 
ment involved  the  determination  with  considerable  accuracy  of  the 
geographical  position,  or  in  other  words  the  latitude  and  longi- 
tude, of  two  points,  and  then  a  geodetic  or  trigonometrical 
survey  which  took  into  consideration  the  curvature  of  the  earth's 
surface,  measuring  the  actual  distance  between  them  in  terms  of 
a  unit  of  length  selected  for  that  purpose  and  represented  by  a 
standard  which  was  employed  in  the  measurement  of  a  base- 
line. The  distance,  as  found  by  the  triangulation,  could  then  be 
compared  with  the  difference  in  latitude  between  the  two  points, 
and  thus  the  actual  distance  in  degrees  could  be  obtained  in 
terms  of  the  selected  linear  standard.  The  other  invariable 
standard  of  length  was  that  of  a  pendulum,  which  in  a  given 
place  executed  its  vibrations  always  in  the  same  time.  By  the 
law  of  the  pendulum,  the  time  of  vibration  is  inversely  pro- 
portional to  the  square  root  of  the  acceleration  due  to  gravity,  and 
directly  as  the  square  root  of  the  length.  Consequently,  being 
able  to  measure  time,  and,  assuming  that  the  acceleration  of 
gravity  at  a  given  point  is  constant,  it  is  possible  to  determine  or 
reproduce  accurately  a  given  length  by  this  instrumentality. 

After  considering  the  invariability  of  the  original  standard,  the 
next  important  matter  to  bear  in  mind  is  the  symmetry  and 
convenience  in  actual  use  of  any  system  of  measures  which  is 
based  thereon.  In  the  light  of  the  development  of  the  science  of 
arithmetic  and  of  the  popular  methods  of  reckoning,  it  can  be 
safely  said  that  the  decimal  system  for  money,  weights,  and 
measures,  must  stand  as  the  most  simple  and  useful.  Therefore 


DEVELOPMENT   OF  THE   METRIC   SYSTEM        43 

in  considering  the  genesis  of  the  modern  metric  system,  as  a 
universal  system  founded  on  an  invariable  standard  and  sym- 
metrically and  conveniently  developed,  it  is  necessary  to  go  back 
to  Gabriel  Mouton,  Vicar  of  St.  Paul's  Church,  Lyons,  who  first 
proposed  in  1670  a  comprehensive  decimal  system  having  as  a  basis 
the  length  of  an  arc  of  one  minute  of  a  great  circle  of  the  earth. 
One  minute  of  arc  would  give  the  length  of  a  milliare  or  mille, 
which  would  be  subdivided  decimally  into  centuria,  decuria,  virga, 
virgula,  decima,  centesima,  millesimal  The  virga  and  mrgula  would 
be  the  chief  units  of  the  system  corresponding  to  the  toise  and  the 
foot  then  in  use.  This  geometric  foot  (virgula  geometrica)  was 
further  defined  by  Mouton  as  corresponding  to  the  length  of  a 
pendulum  making  3,959*2  vibrations  in  a  half  hour  at  Lyons.2 
This  proposition  contained  essentially  the  germ  of  the  modern 
metric  system  and  Mouton's  suggestion  of  the  pendulum  was  soon 
repeated  by  Picard  (1671),  and  by  Huygens3  (1673).  The  former 
said4  "  The  length  of  a  pendulum  beating  seconds  of  mean  time 
would  be  called  the  astronomical  radius  (Rayon  Astronomique),  of 
which  the  one-third  would  be  the  universal  foot :  the  double  of 
the  astronomical  radius  would  be  the  universal  toise,  which  would 

be  at  Paris  as  881  to  864 If  we  should  find  by  experience 

that  the  pendulums  were  of  different  lengths  in  different  places, 
the  supposition  we  had  made  touching  a  universal  measure 
depending  on  the  pendulum  would  not  stand,  but  it  would  not 
alter  the  fact  that  in  each  place  the  measure  would  be  perpetual 
and  invariable." 

^ee  Bassot,  "Historical  Sketch  of  the  Foundation  of  the  Metric  System," 
Annuaire  pour  Van  1901,  public  par  le  Bureau  des  Longitudes,  Paris.  Translated 
in  School  of  Mines  QiLarterly  (New  York),  vol.  iii.  No.  1,  Nov.,  1901. 

2  Mouton,  Observationes  diametrorum  Solis  et  Lunae .  . .  Huic  adjecta  est  brevis 
dissertatio  de .  .  .  nova  menaurarum  geometricarum  idea  (Lyons,  1670),  p.  427.     In 
reference  to  Mouton's  work  an  interesting  paper  by  Professor  J.  H.  Gore,  "The 
Decimal  System  of  Measures  of  the  Seventeenth  Century,"  in  the  American  Journal 
of  Science   (Third    Series,    vol.    xli.    Jan.,   1891,   p.  22),   should   be    consulted. 
Professor  Gore  quotes  from  Mouton's  writings  and  describes  his  researches  in  order 
to  show  that  the  essential  features  of  the  Metric  System  were  first  announced  by 
him.     Furthermore  he  does  not  consider  that  due  credit  was  given  by  the  French 
scientists  who  founded  the  system  and  made  use  of  Mouton's  ideas. 

3  Horologium  Oscillatorium,  4  prop.  25  (Paris,  1673). 

4  Mesure  de  la  Terre,  reprinted  in  Anciens  Memoires,  vol.  vii.  p.  133. 


44       EVOLUTION   OF   WEIGHTS   AND   MEASURES 

Similar  in  character  to  the  plan  of  Mouton,  but  considerably  later 
(1720),  was  a  proposition  made  by  Cassini,  in  his  celebrated  work, 
De  la  grandeur  et  de  la  figure  de  la  Terre  (pp.  158,  159),  recom- 
mending the  adoption  of  a  unit  known  as  the  pied  geometrique. 
This  was  equal  to  ^Q-^  part  of  a  minute  of  arc  of  a  great  circle, 
and  6  pieds  formed  a  toise.  This  foot  had  a  length  almost  half 
that  given  by  the  i  Q  o  b'b  0  o  o  Par^  °^  ^he  ra(lius  of  the  earth. 

Subsequently  another  plan  involving  the  length  of  the  second's 
pendulum  as  a  unit,  was  brought  forward  and  developed  by  Du  Fay, 
and  this,  after  his  death,  was  elaborated  and  continued  by  La 
Condamine  (1747),1  who  provided  against  the  variation  in  length 
at  various  latitudes  by  taking  as  his  unit  the  length  of  the 
second's  pendulum  at  the  equator  (36  inches  7*15  lignes  of  the  toise 
of  Peru),  which  he  together  with  Godin  and  Bouguer  had  quite 
accurately  determined  at  Quito,  while  engaged  in  measuring  an 
arc  of  meridian  at  the  equator  in  1735-1737.  La  Condamine  also 
appreciated  the  advantages  of  the  decimal  division  of  measures  of 
length,  and  saw  the  necessity  for  reforms  in  the  measures  of  area, 
capacity,  weight,  etc.,  so  that  all  might  be  brought  into  harmony 
with  the  linear  measures,  and  thus  be  equally  stable  and  invariable. 
He  was  farsighted  enough  to  suggest,  what  has  since  been  such  a 
valuable  feature  of  the  metric  system,  namely  the  advantages  of 
international  joint  effort  in  making  the  desired  changes,  and 
advocated  consulting  with  the  academies  of  foreign  countries  in 
this  matter. 

Worthy  of  record  also  is  the  proposition  made  by  M.  Prieur 
Du  Vernois,2  who  urged  as  the  unit  of  length,  that  of  the  second's 
pendulum,  in  preference  to  that  of  a  fraction  of  an  arc  of  meridian, 
on  the  ground  that  the  former  could  be  reproduced  more  readily. 
He  advocated  taking  the  length  of  the  pendulum  at  a  single  point, 
suggesting  the  Eoyal  Observatory  at  Paris,  and  then  making  a 
standard  of  platinum,  correct  at  a  certain  temperature  such  as  10°, 
which  would  be  deposited  in  the  Hotel  de  Ville.  One-third  of  the 
length  of  this  standard  would  be  the  French  or  natural  foot, 
which  would  be  divided  into  10  inches,  each  inch  in  turn  being 

1  Me'moires  de  V Academic  des  Sciences,  p.  489,  1747. 

2  See  Prieur  (Du  Vernois),  Memoire,  sur  la  ne'cessite'  et  les  moyens  de  rendre 
uniformes  dans  le  royaume  toutes  les  mesures  d'entendue  et  de  pesanteur,  etc.  (Paris, 
1790),  pp.  9-11. 


DEVELOPMENT   OF  THE   METRIC   SYSTEM       45 

divided  into  10  lignes.  Multiplying  the  foot  by  ten  would  give 
the  national  perch,  while  an  area  ten  perches  square  would  be  the 
national  arpent.  Units  of  volume  would  be  measured  by  cubes  of 
lignes,  inches,  and  feet,  and  the  unit  of  mass  would  be  a  national 
pound  corresponding  to  the  mass  of  a  cube  of  distilled  water  at 
some  determined  temperature,  ten  inches  square  on  each  edge. 
Prieur  also  advocated  a  decimal  system  of  money,  in  which  the 
lime  (franc)  was  divided  into  tenth  and  hundredth  parts  known 
as  decimes  and  centimes. 

During  the  eighteenth  century  such  schemes  as  have  just  been 
described  were  proposed  by  scientists  for  the  improvement  of  the 
weights  and  measures,  and  although  they  were  brought  to  the 
attention  of  the  French  Government  they  did  not  meet  with 
such  approval  as  to  secure  their  adoption.  Indeed  there  was  no 
lack  of  plans  proposed  by  the  scientific  men,  and  the  government 
realized  the  necessity  for  uniformity  throughout  the  realm,  but 
the  various  schemes  were  discussed  and  discarded  without  any 
definitive  action,  and,  just  as  in  later  times,  the  difficulties 
attending  the  introduction  of  a  new  system  were  anticipated 
and  feared.  In  fact  Necker,  in  a  report  made  to  Louis  XVI. 
in  1778,  speaks  of  the  proposed  reform  of  weights  and  measures 
with  considerable  diffidence.  He  writes,  "  I  have  occupied 
myself  in  examining  the  means  which  might  be  employed  to 
render  the  weights  and  measures  uniform  throughout  the  king- 
dom, but  I  doubt  yet  whether  the  unity  which  would  result 
would  be  proportionate  to  the  difficulties  of  all  kinds  which  this 
operation  would  entail  on  account  of  the  changing  of  values 
which  would  necessarily  be  made  in  a  multitude  of  contracts,  of 
yearly  payments,  df  feudal  rights  and  other  acts  of  all  kinds.  I 
have  not  yet  renounced  the  project,  and  I  have  seen  with 
satisfaction  that  the  Assembly  of  Haute-Guyenne  have  taken  it 
into  consideration.  It  is  in  effect  a  kind  of  amelioration  which 
can  be  undertaken  partially,  and  the  example  of  a  happy  success 
in  one  province  would  essentially  influence  opinion."1 

With  the  changes  wrought  by  the  Ee volution  it  was  possible 
to  gain  at  the  hands  of  the  public  consideration  for  radical  ideas 
in  science  as  well  as  in  government  and  religion.  The  schemes 

1  Necker,   Compte  rendu  au   Hoi  de  1778,  Bigourdan,   Le   Syst&me  Mdtrique, 
<Paris,  1901),  p.  11. 


46       EVOLUTION   OF   WEIGHTS   AND   MEASURES 

and  discussions  already  mentioned  paved  the  way  for  the  favour- 
able reception  of  a  plan  for  reform  when  it  was  urged  in  the 
National  Assembly  by  a  bold  and  able  leader.  Such  was 
Talleyrand,  then  Bishop  of  Autun,  who  brought  the  matter  to 
the  attention  of  the  National  Assembly  in  April,  1790.  He  not 
only  appreciated  the  necessity  for  a  uniform  system  of  weights 
and  measures  for  France,  but  also  the  desirability  of  a  system 
that  would  be  truly  international  rather  than  merely  the  weights 
and  measures  of  Paris.  He  proposed  as  a  fundamental  unit  the 
length  of  a  pendulum  beating  seconds  at  45°  latitude,  and  as  a 
unit  of  weight  that  of  a  cube  of  water  whose  height  should  be 
one  twelfth  the  length  of  the  pendulum.  New  and  most  careful 
measurements  were  to  be  undertaken  to  determine  the  length  of 
the  pendulum,  and  for  this  purpose  a  joint  commission  of  the 
Paris  Academy  of  Sciences  and  the  Royal  Society  of  London  was 
to  be  established.  Talleyrand's  proposal,  after  being  considered 
by  the  Committee  on  Agriculture  and  Commerce  and  discussed 
in  a  report  by  the  Marquis  de  Bonnay,  was  brought  before  the 
National  Assembly,  where,  in  the  course  of  the  general  discussion 
upon  it,  the  advantages  of  a  decimal  division  were  urged.  The 
report  was  accepted  and  a  decree  was  rendered  on  May  8,  1790, 
which  was  sanctioned  by  Louis  XVI.  on  August  22  of  the  same 
year.  Inasmuch  as  this  decree  describes  with  some  detail  the 
existing  condition  and  the  method  of  making  the  change,  it  is 
given  below  in  full.  It  runs : 

"  The  National  Assembly,  desiring  that  all  France  shall  forever 
enjoy  all  the  advantages  which  will  result  from  uniformity  in 
weights  and  measures,  and  wishing  that  the  relation  of  the  old 
measures  to  the  new  should  be  clearly  determined  and  easily 
understood,  decreed  that  His  Majesty  shall  be  asked  to  give 
orders  to  the  administrators  of  the  different  departments  of  the 
kingdom,  to  the  end  that  they  procure  and  cause  to  be  remitted 
to  each  of  the  municipalities  comprised  in  each  department  and 
that  they  send  to  Paris  to  be  remitted  to  the  Secretary  of  the 
Academy  of  Sciences  a  perfectly  exact  model  of  the  different 
weights  and  elementary  measures  which  are  in  usage. 

"  It  is  decreed  further  that  the  King  shall  also  beg  His 
Majesty  of  Britain  to  request  the  English  Parliament  to  concur 
with  the  National  Assembly  in  the  determination  of  a  natural 


DEVELOPMENT   OF  THE   METRIC   SYSTEM        47 

unit  of  measures  and  weights ;  and  in  consequence,  under  the 
auspices  of  the  two  nations,  the  Commissioners  of  the  Academy 
of  Sciences  of  Paris  shall  unite  with  an  equal  number  of  members 
chosen  by  the  Royal  Society  of  London,  in  a  place  which  shall 
be  respectively  decided  as  most  convenient,  to  determine  at  the 
latitude  of  45°,  or  any  other  latitude  which  may  be  preferred, 
the  length  of  the  pendulum,  and  to  deduce  an  invariable  standard 
for  all  the  measures  and  all  the  weights ;  and  that  after  this 
operation  is  made  with  all  the  necessary  solemnity,  His  Majesty 
will  be  asked  to  charge  the  Academy  of  Sciences  to  fix  with 
precision  for  each  royal  municipality  the  relation  of  the  old 
weights  and  measures  to  the  new  standard,  and  to  compose 
afterward  for  the  use  of  the  municipalities  the  usual  books  and 
elementary  treatises  which  will  indicate  with  clearness  all  these 
propositions. 

"  It  is  decreed  further  that  these  elementary  books  shall  be 
sent  at  the  same  time  to  all  the  municipalities  to  be  distributed : 
at  the  same  time  there  shall  be  sent  to  each  of  the  municipalities 
a  certain  number  of  new  weights  and  measures  which  they  shall 
distribute  gratuitously  to  those  who  would  be  caused  great 
expense  by  this  change ;  and  finally,  six  months  only  after  the 
distribution,  the  old  measures  shall  be  abolished  and  replaced 
by  the  new. 

"  The  National  Assembly  decrees  that  the  Academy,  after  con- 
sultation with  the  officers  of  the  Mint,  shall  offer  their  opinion 
as  to  the  suitability  of  fixing  invariably  the  inscription  of  the 
coined  metal  to  the  end  that  the  kinds  shall  never  be  altered 
except  in  their  weight,  and  whether  it  would  not  be  useful  that 
the  difference  tolerated  in  the  coins  under  the  name  of  remedy 
be  always  beyond  requirement,  that  is  to  say  one  piece  may 
exceed  the  weight  prescribed  by  law  but  must  never  be 
inferior. 

"  Finally,  the  Academy  shall  indicate  the  scale  of  division 
which  it  believes  most  convenient  for  all  weights,  measures 
and  coins." 

Under  the  terms  of  this  decree  the  Academy  took  up  its  work  A 
in  earnest,  and  on  October  27,  1790,  its  committee  consisting  of 
Borda,  Lagrange,  Laplace,  Tillet,  and  Condorcet,  made  a  report  in 
which   they  urged  the  adoption  of  the  decimal  division  of  the 


48       EVOLUTION   OF   WEIGHTS   AND   MEASURES 

moneys,  weights,  and  measures.  This  report  dealt  with  the 
comparative  merits  of  the  decimal  and  duodecimal  system  of 
calculation,  and  discussed  many  of  the  questions  bearing*  on  this 
subject  which  have  been  argued  at  such  length  before  and  since. 
Next  in  importance  after  settling  on  the  principle  of  decimal 
division  was  the  selection  of  a  unit  of  length,  and  a  committee 
consisting  of  Borda,  Lagrange,  Laplace,  Monge,  and  Condorcet, 
presented  a  report  to  the  Academy  on  March  19,  1791,  in  which 
they  stated  that,  in  their  opinion,  the  units  suitable  for  adoption 
as  the  basis  of  a  uniform  and  rational  system  of  weights  and 
measures  were  three  in  number,  as  follows :  the  length  of  a 
second's  pendulum,  the  quadrant  of  a  great  circle  of  the  equator, 
and  the  quadrant  of  a  great  circle  of  meridian.  Considering  the 
relative  advantages  and  drawbacks  of  each  of  these  with  great 
care  and  deliberation,  the  committee  concluded  that  while  the 
length  of  the  second's  pendulum  was  easily  determined  and 
susceptible  of  verification,  it  was  dependent  on  the  acceleration 
due  to  gravity,  and  that  it  was  necessary  to  have  the  position 
specified  exactly.  The  most  desirable  point  would  be  at  45° 
latitude,  a  mean  distance  between  the  equator  and  the  pole.  ^At 
the  latter  points,  owing  to  flattening  of  the  earth  at  the  po|es, 
pendulums  vibrating  with  the  same  period  would  have  unequal 
lengths,  that  at  the  equator  being  shorter  as  the  force  of  gravity 
there  owing  to  the  greater  radius  of  the  earth  is  less  intense. 
But  with  the  pendulum  a  new  and  unlike  element,  namely  the 
second,  is  introduced,  and  this  depends  upon  the  arbitrary 
division  of  the  day.  The  preference  of  the  committee  was  for  a 
terrestrial  arc,  inasmuch  as  it  bore  a  nearer  relation  to  the 
ordinary  method  of  measuring  distances,  and  their  choice  was  in 
favor  of  an  arc  of  a  meridian  rather  than  one  of  the  equator. 
This  decision  was  due  to  the  fact  that  such  an  arc  could  be 
measured  with  greater  facility,  and  also  in  several  countries, 
while  in  addition  no  more  assurance  of  the  regularity  of  the 
equator  than  that  of  a  meridian  could  be  given. 

After  an  arc  had  been  measured  the  length  of  a  quadrant 
could  then  be  computed,  and  one  ten-millionth  of  its  length  could 
be  taken  as  the  base  or  fundamental  unit  of  length.  In  other 
words  the  quadrant  was  to  be  measured  in  a  single  unit  of  length 
on  a  decimal  basis,  instead  of  in  the  former  degrees,  minutes,  and 


DEVELOPMENT   OF  THE   METRIC   SYSTEM        49 

seconds.  The  plan  proposed  by  the  committee  was  to  measure 
an  arc  of  meridian  between  Dunkirk,  on  the  northern  coast  of 
France,  and  Barcelona  on  the  Mediterranean  ^eA,  largely  because 
these  two  places  were  each  situated  at  the  ^ajevel  in  the  same 
medidian,  because  they  afforded  a  suitable  intervening  distance  of 
about  9°  30',  the  greatest  in  Europe  available  for  a  meridian 
measurement,  because  the  country  so  traversed  had  in  part  been 
surveyed  trigonometrically  previously  by  Lacaille  and  Cassini  in 
1739-1740,  and  furthermore  because  such  an  arc  extended  on 
both  sides  of  latitude  45°.  The  committee  outlined  six  distinct 
operations  essential  for  the  work.  They  were  as  follows : 

1.  The  determination   of  the   difference   in   latitude   between 
Dunkirk  and  Barcelona. 

2.  The  measurement  of  the  old  bases. 

3.  The  verification  and  measurement  of  the  series  of  triangles 
used  in  a  previous  survey,  and  extending  the  same  to  Barcelona. 

4.  The  observation  of  the  pendulum  at  45°  latitude. 

5.  Verification  of  the  weight  in  vacuum  of  a  given  volume  of 
distilled  water  at  the  temperature  of  melting  ice. 

6.  Comparison  of   the   old   and  new  measures,  and   the  con- 
struction of  scales  and  tables  of  equalization. 

The  National  Academy  straightway  adopted  the  recommenda- 
tions of  the  committee,  adopting  the  length  of  one  fourth  of  a 
terrestrial  meridian  as  the  basis  for  the  measures  of  length,  and 
providing  for  the  measurement  of  the  arc  from  Dunkirk  to 
Barcelona,  and  the  appointment  of  supervisory  committees  by  the 
Academy  of  Sciences.  This  latter  body  then  addressed  itself  to 
the  consideration  of  a  suitable  nomenclature,  and  fixed  the  length 
of  the  new  unit  provisionally  at  36  inches  11*44  lignes,  and 
assigning  the  name  Metre  to  the  one  ten-millionth  part  of  the 
quadrant  of  the  earth's  meridian.1  The  relations  between  the 
measures  of  length  and  capacity,  capacity  and  weight,  and  weight 
and  money  were  also  considered.  The  provisional  meter  was 
derived  from  a  calculation  of  the  observations  made  by  Lacaille 
when  measuring  a  meridian  in  France  in  1740.  By  this  the 
value  of  one  degree  was  given  as  57,027  toises,  which  multiplied 
by  90  would  give  the  length  of  the  quadrant  or  distance  from 
pole  to  equator,  as  5,132,430  toises.  Taking  the  ten-millionth 


1  Report  of  May  29,  1793. 
D 


50       EVOLUTION   OF    WEIGHTS   AND   MEASURES 


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DEVELOPMENT   OF   THE   METRIC   SYSTEM        51 


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52       EVOLUTION   OF   WEIGHTS   AND   MEASURES 

part  of  this  value,  and  reducing  it  to  the  feet  and  lignes  into 
which  the  toise  was  divided,  the  length  of  3  feet  11*44  lignes 
was  obtained.  To  show  how  little  this  provisional  meter  varied 
from  the  meter  finally  determined  by  the  commission  in  1799,  it 
may  be  stated  that  the  latter  length  in  the  same  units  is  3  feet 
11*296  lignes,  or  a  difference  of  about  *33  millimeters,  an  amount 
considered  quite  insignificant  in  every-day  dealings.  A  standard 
of  the  provisional  meter  in  brass  was  duly  constructed  by  Lenoir 
in  Paris,  and  is  preserved  in  the  Conservatoire  des  Arts  et 
Metiers  at  Paris.1 

The  committee  was  unable  to  decide  definitely  on  a  system  of 
nomenclature,  and  accordingly  proposed  two  schemes :  one,  as 
they  termed  it,  methodical,  in  which  Latin  prefixes  were  used  for 
the  various  units;  the  other  simple  monosyllabic  names  which 
they  believed  would  be  more  readily  adopted  by  the  general 
population.  The  Convention,  which  in  the  meanwhile  had 
replaced  the  National  Assembly,  adopted  the  recommendations 
of  the  committee,  but  preferred  to  use  the  methodical  nomen- 
clature. This  decree  was  dated  August  1,  1793,  and  called  atten- 
tion to  the  importance  of  the  steps  being  taken  to  secure 
uniformity  of  weights  and  measures  in  France,  and  outlined 
the  methods  of  practically  establishing  the  new  system  through- 
out the  country.  The  suppression  of  the  Academy  of  Sciences 
occurred  a  few  days  (August  8,  1793)  after  passing  this  decree, 
and  this  event,  together  with  various  legislative  enactments  from 
time  to  time,  had  the  effect  of  causing  changes  in  the  personnel 
of  the  scientific  staff  entrusted  with  the  development  of  the 
system  and  some  differences  in  the  method  of  procedure.  The 
place  of  the  Academy  was  taken  by  a  newly  constituted  National 
Institute  of  Sciences  and  Arts,  which  continued  the  scientific 
oversight,  and  in  general  the  undertaking  was  pushed  forward  as 
rapidly  as  is  possible  with  work  of  such  character. 

As  showing  the  extent  to  which  the  desire  for  changes  and 
reforms  was  being  manifested  in  France  at  this  time,  it  may  not 
be  inappropriate  to  refer  at  this  point  to  the  innovations  intro- 
duced in  the  calendar  whereby  the  decimal  system  was  here 
applied  also.  By  a  decree  of  November  24,  1793,  time  was  to  be 

^igourdan,  Le  Systeme  Metrique  (Paris,  1901),  chap.  ix.  pp.  90-93.     M^chain 
and  Delambre,  Base  du  Systeme  Metrique  (Paris,  1806-1810),  vol.  iii.  pp.  673-690. 


DEVELOPMENT   OF   THE   METRIC   SYSTEM        53 

reckoned  from  the  establishment  of  the  French  Eepublic,  Sep- 
tember 22,  1792,  the  day  of  the  autumnal  equinox.  The  year  as 
formerly  was  to  be  divided  into  twelve  months,  but  each  of  these 
was  to  be  divided  into  three  weeks,  or  decads,  of  ten  days  each. 
Each  day  was  to  be  divided  into  ten  hours,  and  each  hour  into 
one  hundred  minutes  of  one  hundred  seconds  each.  A  picturesque 
feature  was  the  grouping  of  the  months  according  to  the  seasons 
with  a  different  termination  for  the  names  of  each  season.  Thus, 
beginning  with  the  autumn  equinox,  Vendemiaire  was  the  month 
of  vintage,  and  was  followed  by  Brumaire;  the  month  of  fogs,  and 
Frimaire,  the  month  of  incipient  cold.  At  the  winter  solstice 
came  Mvose,  the  month  of  snow,  and  then  Pluviose,  the  month  of 
rain,  and  Ventose,  the  month  of  wind.  The  spring  months  were, 
Germinal,  the  month  of  buds ;  Floreal,  the  month  of  blossoms ; 
and  Prairial,  the  month  of  flowering  fields.  In  the  summer  came 
Messidor,  the  month  of  harvests ;  Thermidor,  the  month  of  heat ; 
and  Fructidor,  the  month  of  fruits. 

This  changed  calendar  was  used  until  1806,  when  the  Gregorian 
calendar  was  resumed,  but  the  division  of  the  day  into  100,000 
parts  was  abandoned  in  1795.  The  lack  of  success  of  this  method 
of  dividing  time  can  readily  be  explained,  and  by  reasons  which 
have  but  little  bearing  on  the  science  of  metrology.  The  doing 
away  with  the  Christian  Sabbath,  the  addition  of  a  festival  season, 
the  changing  of  well-established  modes  of  life  by  legislative  enact- 
ment could  hardly  but  be  expected  to  fail  of  adoption.  Further- 
more, the  Gregorian  calendar  was  at  this  time  practically  universal, 
and  furnished  no  inconvenience  either  to  scientific  men  or  to  the 
general  public.  It  was  a  case  of  change  merely  for  the  sake  of 
innovation,  and  as  such  was  destined  to  fail. 

The  time  being  ripe  for  further  and  more  definite  legislation 
on  the  subject  of  the  new  scheme  of  weights  and  measures,  after 
Prieur  (de  la  Cote  d'Or)  had  made  a  full  and  comprehensive 
report  describing  the  status  of  the  work  of  establishment  and 
recommending  a  new  system  of  nomenclature,  the  Convention 
enacted  the  Law  of  18  Germinal  an  III.  (April  7,  1795),  which 
defined  precisely  the  different  units,  provided  for  standards,  and 
the  proper  distribution  of  secondary  standards,  and  the  exact 
determination  of  the  units  of  length  and  mass  according  to  the 
original  plan.  Article  5  of  this  decree  is  worth  quoting  in  full, 


54       EVOLUTION   OF   WEIGHTS   AND   MEASURES 

as  it  gives  precise  definitions  of  the  elementary  units  of  the 
metric  system.  It  reads  : 

"  Art.  5. — The  new  measures  will  be  distinguished  by  the  name 
of  measures  of  the  Eepublic :  their  nomenclature  is  definitely 
adopted  as  follows : 

"  Meter,  the  measure  of  length  equal  to  the  ten-millionth  part 
of  a  terrestrial  meridian  contained  between  the  north  pole  and 
the  equator. 

"  Are,  the  measure  of  area  for  land  equal  to  a  square  ten 
meters  on  each  side. 

"  Stere,  the  measure  designed  especially  for  fire- wood,  and  which 
shall  be  equal  to  a  meter  cube. 

"  Liter,  the  measure  of  capacity  both  for  liquids  and  dry 
materials,  whose  extent  will  be  that  of  a  cube  of  one-tenth  of  a 
meter. 

"  Gramme,  the  absolute  weight  of  a  volume  of  pure  water  equal 
to  a  cube  of  one-hundredth  part  of  a  meter,  and  at  the  tempera- 
ture of  melting  ice. 

"Finally  the  unit  of  coinage  shall  take  the  name  of  franc  to 
replace  the  livre  used  until  to-day." 

Greek  prefixes  were  provided  to  denote  the  multiples  of  the 
various  units  and  the  Latin  prefixes  for  the  subdivisions,  while  in 
the  measures  of  weight  and  capacity,  provision  was  made  in  addi- 
tion for  double  and  half  measures. 

Under  the  provision  of  this  law,  the  scientific  work  was  taken 
up  with  vigor,  and  the  Government  appointed  a  commission  of 
twelve  to  complete  the  original  determinations  of  length  and 
mass.  This  body  included  Berthollet,  Borda,  Brisson,  Coulomb, 
Delambre,  Haiiy,  Lagrange,  Laplace,  Mechain,  Monge,  Prony,  and 
Yandermonde,  all  of  whom  had  been  interested  actively  in  the 
work  previously  accomplished.  This  commission  was  then  sub- 
divided, Delambre  and  Mechain  taking  charge  of  the  astronomical 
and  geodetic  work,  Borda,  Haiiy,  and  Prony  of  the  determination 
of  the  units  of  weight,  Borda  and  Brisson  of  the  construction  and 
verification  of  the  provisional  meter,  and  Berthollet,  Monge  and 
Vandermonde  of  the  construction  of  the  definite  meter.  The 
length  of  a  second's  pendulum  had  already  been  determined  by 
Cassini  and  Borda  at  Paris,  and  was  found  to  be  equal  to  3  feet 
8*5593  lignes  of  the  toise  of  Peru. 


DEVELOPMENT   OF   THE   METRIC   SYSTEM        55 

The  measurement  of  the  arc  of  meridian  was  the  most  impor- 
tant of  the  duties  of  the  commission,  and  involved  a  vast  amount 
of  labor,  both  in  observations  in  the  field  and  in  the  reduction 
and  calculation  of  these  observations.  The  work  was  originally 
commenced  in  1792  by  Me" chain  and  Delambre,  and  was  carried 
on  by  them  through  various  vicissitudes  caused  by  changes  in 
political  conditions,  with  their  consequent  effect  on  the  general 
and  scientific  plans  for  the  various  operations. 

Before  describing  their  work,  however,  it  may  be  of  advantage  to 
outline  the  underlying  principles  of  a  geodetic  or  trigonometrical 
survey  such  as  is  necessary  to  determine  the  length  of '  an  arc 
on  the  surface  of  the  earth.  Such  a  survey  naturally  involves 
the  measurement  of  considerable  distances,  taking  into  considera- 
tion the  curvature  of  the  earth's  surface,  and  requires  a  system 
or  network  of  triangles  connected  one  with  another  by  means  of 
common  sides.  The  vertices  are  stations  usually  situated  on 
some  high  altitude,  or  at  any  event  so  selected  that  each  is 
visible  with  a  telescope  from  several  others.  Always  at  one  end, 
and  often  at  or  near  both  ends,  there  is  what  is  known  as  a  base- 
line, a  horizontal  distance  on  level  ground  actually  measured 
with  a  linear  standard  to  as  high  a  degree  of  precision  as  is 
possible.  This  involves  measuring  a  distance  of  from  one  to  ten 
kilometers  by  means  of  rods,  bars,  or  steel  tapes,  whose  lengths 
have  been  determined  with  great  accuracy  at  a  standard  tempera- 
ture, to  which  by  correction  the  actual  measurements  may  be 
reduced.  Care  must  be  taken  to  place  the  standards  perfectly 
horizontal  and  end  to  end  when  they  are  being  moved  over  the 
measured  distance,  or  to  make  suitable  corrections,  and  to 
observe  the  temperature.  In  this  way  the  base  line,  or  one  side 
of  the  triangle,  marked  in  the  accompanying  diagram  by  a 
heavy  line,  is  accurately  determined,  and  it  is  advantageous 
in  an  extended  survey  to  have  the  base  lines  at  or  near  sea-level. 

After  the  base  line  is  determined,  then  the  triangulation  may 
be  reduced  and  the  distance  calculated  between  the  remote  ends 
•of  the  arc.  If  reference  is  made  to  plate  vii.  vol.  i.  of  the 
work x  of  Delambre  and  Mechain  here  reproduced,  it  will  be 
possible  to  illustrate  the  general  method.  The  base  shown 
between  Salces  and  Vernet  is  near  Perpignan,  in  the  south  of 

1  Le  Base  du  Systeme  Metrique,  vol.  i. 


56      EVOLUTION   OF   WEIGHTS   AND   MEASURES 

France,  and  at  the  end  of  the  old  arc  previously  measured.  This 
distance  is  actually  measured  with  the  base  line  apparatus. 
Then  by  means  of  a  divided  circle,  capable  of  measuring  angles 
in  both  a  horizontal  and  vertical  plane,  and  transit  or  theodolite 
placed  at  the  "  terme  boreal  "  (north  end  of  the  base  line),  the 
angle  between  the  direction  to  Mt.  d'Espira  and  to  Mt.  Forceral 
is  measured,  and  then  at  the  "  terme  austral "  the  corresponding 
similar  angles  are  measured.  Thereupon  the  instrument  is  taken 
to  Mt.  d'Espira  and  the  angles  around  that  point  determined. 
This  is  the  beginning  of  a  long  series  of  angle  determinations  at 
all  the  points  of  observation,  as  Mt.  de  Tauch,  Pic  de  Bugarach, 
Mt.  Alaric,  Carcassonne,  etc.  All  of  the  measurements  are  con- 
tinually checked  by  the  fact  that  the  sum  of  all  the  angles 
around  a  single  point,  as  Mt.  Alaric,  must  equal  360°,  and  that 
the  sum  of  the  three  angles  in  any  triangle  must  equal  180°.  In 
any  triangle,  if  one  side  and  two  angles,  or  two  sides  and  one 
angle,  are  known,  then  it  is  a  simple  matter  to  calculate  the 
other  parts. 

In  this  way  it  is  not  only  possible  to  calculate  the  length  of 
the  sides  of  all  the  numerous  triangles  formed  between  Barcelona 
and  Dunkirk,  but  also  the  projection  of  each  upon  the  true  north 
and  south  meridian.  For  example,  as  soon  as  the  linear  distance 
from  Mt.  Alaric  to  St.  Pons  is  known,  and  the  angle  which  the 
direction  makes  with  the  true  meridian,  then  it  is  simple  to- 
calculate  how  far  one  is  north  of  the  other,  or  in  other  words, 
the  section  of  the  meridian  corresponding  to  the  distance  of  St. 
Pons  due  north  of  Mt.  Alaric.  Thus  ultimately  the  distance  of 
Dunkirk  due  north  of  Barcelona  is  calculated.  The  numerous 
triangles  give  continual  checks  upon  the  work,  as  do  also  other 
base  lines  distributed  along  the  line  of  triangulation. 

The  foregoing  gives  the  merest  outline  of  the  work  of  triangu- 
lation, as  there  are  numerous  refinements  and  modifications 
involved  in  both  observation  and  computation,  which  make  the 
calculation  one  of  no  small  magnitude.  This,  however,  is  but 
half  of  the  work.  There  must  be  found,  with  an  equal  degree  of 
precision,  the  geographical  position,  or,  more  particularly,  the 
latitude,  of  the  two  extremities  of  the  meridian  by  astronomical 
methods.  In  kind  this  is  similar  to  the  finding  of  the  position 
of  a  vessel  at  sea,  but  more  refined  methods  of  observation  are 


lf  de  Tauch 
^ 


Salces 


herme  boreal 


i — 'Yernet- 

M  Forceral  herme  aus^^a» 


58      EVOLUTION   OF   WEIGHTS   AND   MEASURES 

necessary,  and,  at  the  present  day,  the  use  of  the  zenith  telescope 
is  considered  the  most  accurate  of  the  several  methods  of  deter- 
mining the  latitude  of  a  place. 


At  the  time  of  the  measurement  of  the  Dunkirk-Barcelona  arc, 
however,  the  astronomers  used  the  method  of  upper  and  lower 
transits  of  certain  stars  near  the  north  pole  of  the  heavens. 
Keferring  to  the  accompanying  figure,  NDBES  represents  a 


DEVELOPMENT   OF  THE   METRIC   SYSTEM        59 

meridian  of  longitude  through  the  place,  D,  the  latitude  of  which 
is  sought.  That  is,  the  plane  of  the  paper  is  a  plane  through  the 
axis  of  the  earth  NS  and  the  place  D.  Evidently  then  the  angle 
DCE  is  the  latitude  of  the  place  D,  and  the  angle  DON  is  called 
the  colatitude.  If  the  line  DM  indicates  the  direction  in  which 
a  star  appears,  as  seen  from  D  at  the  instant  when  it  passes  the 
meridian,  then  the  angle  ZDM  may  be  observed,  and  is  called  the 
zenith  distance  of  the  star.  The  lines  DP,  DP'  and  SON  are 
parallel,  and  indicate  the  direction  to  the  celestial  pole,  that  is, 
to  the  point  where  the  axis  NS  pierces  the  heavens,  then  the 
angle  ZDP  is  equal  to  DON  the  colatitude  of  the  place.  The 
angle  MDP  is  the  polar  distance  of  the  star. 

A  series  of  determinations  of  the  zenith  distance  of  Polaris,  the 
"  north  star,"  made  on  Jan.  17th,  1796,  at  Dunkirk,  for  the  upper 
transit,  gave  37°  11'  44"*36.  Adding  to  this  the  pole  distance  of 
Polaris,  1°  46'  39"'60,  gives  the  colatitude  38°  57'  44"'36,  and  the 
latitude,  or  90°  minus  the  latitude,  51°  2'  15"*64.  In  the  case  of 
<a  lower  transit,  where  the  star  crosses  the  meridian  below  the 
pole,  the  pole  distance  would  be  subtracted  from  the  zenith 
distance.  That  is  to  say,  Z'DP'  =  Z'DM'  -  M'DP'.  A  similar 
determination  at  Barcelona,  made  on  Dec.  17th,  1793,  gave  as 
the  latitude  of  that  place,  41°  22'  47"'83.  This  would  give  as 
the  difference  of  latitude  between  Dunkirk  and  Barcelona, 
9°  39'  27"-81. 

A  final  determination  of  the  difference  of  latitude  between 
Dunkirk  and  Montjouy  (Barcelona)  90>67380,  and  the  distance, 
measured  in  toises,  was  found  to  be  551  584*72.  If  the  refine- 
ments of  the  polar  flattening  of  the  earth,  etc.,  are  neglected  for 
the  moment,  then  551  58472  divided  by  9'67380  would  give 
57  018*7  as  the  number  of  toises  in  one  degree  of  latitude.  This 
number,  570187,  multiplied  by  90,  gives  5  131  680.  One  ten- 
millionth  part  of  this,  or  0*5131680  of  a  toise,  would  then  be  the 
ideal  meter.  Naturally,  in  the  actual  calculation,  all  the  cor- 
rections and  refinements  were  applied. 

It  must  be  remembered  that  in  making  these  measurements 
much  depends  upon  the  accuracy  of  graduation  of  the  circles,  and 
that  many  measurements  must  be  made  and  an  average  taken  so 
as  to  obtain  in  each  instance  a  mean  value.  The  errors  can  be 
distributed  by  the  two  considerations  referred  to  above,  that  the 


60       EVOLUTION   OF   WEIGHTS   AND   MEASURES 

sum  of  all  the  angles  around  a  point  must  be  360  degrees,  and 
that  the  sum  of  the  three  interior  angles  of  any  triangle  must 
equal  180  degrees.  Furthermore,  when  the  observations  are 
reduced,  allowance  must  be  made  for  the  difference  in  elevation  of 
the  stations  and  for  the  curvature  of  the  earth,  which,  amounting 
to  as  much  as  7  inches  for  each  mile,  becomes  an  important 
quantity  in  an  extended  survey.  Triangulations  analogous  to 
those  here  indicated,  carried  out  over  the  whole  surface  of  a 
country,  are  the  basis  of  all  accurate  map  making,  and,  in  the 
United  States,  an  arc  of  longitude  has  been  measured  which 
extends  across  the  continent. 

The  task  of  measuring  the  French  meridian  was  divided  by 
Delambre  and  Mechain,  the  former  being  assigned  the  northern 
portion  between  Dunkirk  and  Eodez,  a  distance  of  380,000  toises, 
while  to  Mechain  was  given  from  Rodez  to  Barcelona,  a  distance 
of  170,000  toises.  The  reason  for  this  unequal  division  was  that 
the  northern  part  of  the  meridian  was  situated  in  a  much  more 
accessible  country,  while  Mechain's  portion  was  in  the  moun- 
tainous region  of  Spain.  In  addition,  the  northern  part  had 
been  measured  twice  previously,  and  the  stationslmd  been 
selected  and  recorded.  On  June  10,  1792,  the  Jjplr issued  a 
proclamation,  in  which  Delambre  and  Mechain  jrere  commended 
to  the  good  offices  of  government  officials  and  o&izens  generally, 
and  various  rights  and  privileges  were  secured  to  them.  Both 
scientists  straightway  proceeded  to  their  duties,  but,  owing  to  the 
turbulent  conditions  in  the  country,  due  to  the  Revolution,  they 
encountered  from  the  beginning  constant  embarrassment  and 
difficulties.  In  addition  to  being  arrested  and  deprived  of 
ordinary  facilities  to  carry  on  their  work,  they  met  with  little 
sympathy  and  co-operation  on  the  part  of  officials  and  people,  and 
experienced  great  difficulty  in  erecting  and  maintaining  their 
signals,  which  were  oftentimes  believed  to  have  been  built  for 
purposes  of  military  communication. 

Mechain  in  Spain  had  a  certain  amount  of  assistance  from  the 
government  of  that  country,  but  here,  as  in  southern  France,  he 
was  harassed  and  interfered  with  by  political  troubles.  In  fact, 
these  two  resolute  engineers  experienced  almost  incredible 
difficulties,  being  arrested  by  the  various  governing  bodies  that 
were  at  that  time  successively  administering  the  affairs  of  France, 


DEVELOPMENT   OF  THE    METRIC   SYSTEM        61 

deprived  of  liberty  and  freedom,  prevented  from  working  by 
accident  and  disease,  and,  in  short,  accomplishing  most  creditable 
results  under  remarkably  adverse  circumstances. 

Finally,  in  November,  1798,  Mechain  and  Delambre,  having 
completed  their  work,  arrived  at  Paris  with  a  record  of  their 
observations,  and  an  international  commission  invited  by  the 
Directory  proceeded  to  examine  and  approve  the  geodetic  and 
other  scientific  work  accomplished  in  laying  the  foundation  for 
the  metric  system.  This  commission  consisted  of  delegates  from 
the  Batavian  Eepublic,  the  Cis- Alpine  Kepublic,  Denmark,  Spain, 
Switzerland,  the  Liguriaii  Eepublic,  Sardinia  (later  from  the  pro- 
visional government  of  Piedmont),  the  Roman  Republic,  and  the 
Tuscan  Republic,  in  addition  to  a  French  Committee  composed  of 
the  physicists  and  mathematicians  who  had  been  chiefly  concerned 
with  the  development  of  the  system.  The  commission  divided 
itself  into  three  sections,  each  of  which  carried  on  a  most 
thorough  examination  of  the  work  already  done,  and  made 
further  calculations  and  verifications  to  establish  its  accuracy  and 
reliability.1 

The  first  section  made  a  comparison  of  the  bar  used  in  measur- 
ing the  length  of  the  two  bases  at  Melun  and  Perpignan,  and 
found  that  it  corresponded  exactly  with  the  toise  of  Peru. 
Examining  the  toise  of  Mairan,  constructed  from  the  length  of 
the  pendulum  beating  seconds  at  Paris,  it  was  found  to  be  '03413 
line  shorter  than  the  toise  of  Peru.  The  second  section  studied 
the  measurement  of  the  arc  of  meridian  and  the  actual  length  of 
the  meter,  measuring  the  bases,  examining  the  angles  of  each 
triangle,  and  finally  computing  separately  their  dimensions,  em- 
ploying different  tables  of  logarithms.  The  report  which  was 
prepared  by  Van  Swinden,  the  delegate  of  the  Batavian  Republic, 
one  of  the  committee  to  whom  was  assigned  the  actual  calcula- 
tion, shows  how  carefully  the  work  had  been  done,  for,  employing 
the  base  at  Melun  as  a  starting  point  in  computing  the  triangles, 
it  was  found  that  the  difference  between  the  computed  and 
measured  lengths  of  the  base  at  Perpignan  was  '160  toise  (12*28 
inches  =  31*1 9  cm.).  When  it  is  remembered  that  the  length  of 
the  Perpignan  base  was  6006*25  toises,  and  that  of  Melun  6075*9 

1  For  a  full  account  of  this  work  reference  should  be  made  to  Mechain  and 
Delambre,  Base  du  Systtme  Metrique  (Paris,  1806-1810),  vol.  iii. 


62       EVOLUTION   OF   WEIGHTS   AND   MEASURES 

toises,  and  that  they  were  550,000  toises  apart,  the  accuracy  of 
the  measurement  may  be  appreciated. 

The  flattening  of  the  earth  was  also  computed,  employing  the 
present  measurements  in  connection  with  those  made  in  Peru, 
and  it  was  found  to  be  3-J^.1  The  most  important  result  was 
the  calculation  of  the  length  of  the  quadrant  of  the  earth's 
meridian,  5,130,740  toises,  which  straightway  gave  3  feet  11*296 
lignes  as  the  true  length  of  the  meter  instead  of  3  feet  11*442 
lignes,  the  length  of  the  provisional  meter  provided  by  the  law  of 
August  1,  1793. 

The  third  section,  for  which  Tralles,  the  Swiss  scientist,  pre- 
pared the  report,  considered  the  determination  of  the  unit  of 
weight  and  the  construction  of  the  standard  kilogram  which  had 
been  prepared  by  Lefevre-Gineau,  according  to  plans  made  by 
Lavoisier  and  Hatiy,  who  performed  the  first  experiments  for 
this  determination.2  The  preparation  of  this  standard  required 
much  elaborate  experimental  work,  and  it  was  finally  ascertained 
that  the  weight  of  a  cubic  decimeter  of  distilled  water  at  it& 
temperature  of  maximum  density  and  weighed  in  vacuo,  was. 
18,827*15  grains,  the  mean  of  the  sum  of  the  weights  of  Charle- 
magne, which  had  been  employed  as  the  French  standard  for 
over  500  years.  While  it  is  not  possible  here  actually  to  describe 
this  determination  of  the  unit  of  weight,  nevertheless  it  is  inter- 
esting to  record  that  Lefevre-Gineau  and  his  assistant  Fabbroni 
discovered  that  the  maximum  density  of  water  was  reached  at 
4°  Centigrade. 

From  the  sectional  reports  just  mentioned,  a  general  report 
was  compiled  by  Van  Swinden  and  presented  to  the  Instituted 
The  actual  meter  standards  were  then  constructed  by  Lenoir  and 
carefully  compared  with  the  toise  standards.  A  platinum  meter 
was  adopted  as  the  true  meter,  and  wTas  deposited  in  the  Archives 
of  State,  whence  it  was  subsequently  known  as  the  Meter  of  the 
Archives.  Two  other  platinum  standards4  were  constructed  at  the 

JThe  accepted  value  to-day  is — -,  Clarke's  Spheroid,  1866. 

294' 9/84 

2  See  Dumas,  Lavoisier's  Works,  vol.  v. 

3  See  Mechain  and  Delambre,  Base  du  Systeme  Metrique,  vol.  iii.  p.  592. 

4  See  C.  Wolf,  "Recherches  historiques  sur  les  etalons  de  poids  et  mesures  de 
1'Observatoire,"  Ann.  de  I'Observatoire,   Mem.   xvii.  p.  52,  1883  ;   also   Ann.  de 
Chim.  et  Phys.,  5  s.  vol.  xxv.  p.  5,  1882. 


DEVELOPMENT   OF  THE   METRIC   SYSTEM        63 

same  time,  and  are  now  known  as  the  Meters  of  the  Conservatory 
and  Observatory  respectively.  Iron  standards  were  constructed 
also,  and  were  distributed  among  the  delegates.  There  was  also 
constructed  at  the  same  time  a  platinum  kilogram,  and  these 
standards  (kilogram  and  meter)  were  formally  presented  by  a 
delegation  of  the  Institute  to  the  Corps  Legislatif  on  June  22, 
1799,  and  after  being  duly  received  were  deposited  in  the 
Archives  of  the  Eepublic.  On  December  10  of  the  same  yeiP 
by  statute  the  provisional  meter  was  abolished,  and  the  new 
meter  and  kilogram  definitely  fixed  and  defined,  and  the  stan- 
dards presented  by  the  Institute  to  the  Kepublic  were  adopted  as 
the  definite  standards  of  weight  and  length. 

This  act  was  known  as  the  law  of  the  19  Frimaire,  year  VIII., 
and  is  as  follows.1  "  Article  first. — The  provisional  determination 
of  the  length  of  the  meter  at  3  pieds,  11*44  lignes,  ordained  by 
the  laws  of  Aug.  1st,  1793,  and  the  18th  Germinal,  year  III. 
(April  7,  1795),  stands  revoked  and  void.  The  said  length,  form- 
ing the  ten-millionth  part  of  the  arc  of  the  terrestrial  meridian, 
comprised  between  the  North  Pole  and  the  Equator,  is  definitely 
fixed,  in  its  relation  with  the  old  measures,  at  3  pieds,  11  '296  \ 
lignes. 

"  Article  second. — The  meter  and  the  kilogram  in  platinum, 
transmitted  the  four  Messidor  last,  to  the  Corps  Legislatif,  by 
the  National  Institute  of  Sciences  and  Arts,  are  the  definite 
standards  of  the  measures  of  length  and  of  weight  throughout  the 
Eepublic.  Some  exact  copies  of  the  same  will  be  put  in  the 
hands  of  the  Consular  Commission,  in  order  to  serve  as  models 
for  the  construction  of  new  measures  and  new  weights.2 

"  Article  third. — The  other  dispositions  of  the  law  of  the  18 
Germinal,  year  III.,  concerning  all  that  is  relative  to  the  Metric 
System,  as  well  as  to  the  nomenclature  and  the  construction  of 
the  new  weights  and  the  new  measures,  will  continue  to  be 
observed." 

Provision  was  made  (Article  IV.)  for  a  commemorative  medal, 
which,  however,  was  never  made  officially,  and  not  actually  until 

'Bigourdan,  Le  Systeme  Metrique  (Paris,  1901),  pp.  176-177. 

2  This  article  was  repealed  in  the  law  of  July  11,  1903,  by  which  the  inter- 
national meter  and  kilogram  were  officially  recognized,  and  the  French  copiea 
(meter  8  and  kilogram  35)  were  made  the  national  standards. 


64       EVOLUTION   OF   WEIGHTS   AND   MEASURES 

1837,  when  the  ideas  of  the  Institute  in  regard  to  such  a  medal 
were  carried  out  by  MM.  Gonon  and  Penin. 

With  the  scientific  determination  of  the  units  and  the  con- 
struction of  the  standards  accomplished,  there  remained  but  to 
effect  the  general  adoption  of  the  new  weights  and  measures. 
Several  conditions  tended  to  delay  this,  and  at  times  there  was 
even  pronounced  opposition.  Chief,  perhaps,  was  the  change  in 
political  conditions  occurring  in  France,  and  it  was  but  natural 
to  expect  on  the  part  of  an  imperial  government  little  interest  in 
reforms  effected  during  the  republican  regime.  Furthermore, 
there  was  criticism  of  the  system  on  account  of  the  lack  of 
uniformity  and  organization,  as  shown  by  contradictory  legislation, 
and  also  on  account  of  its  nomenclature,  much  opposition  being 
manifested  to  the  use  of  Greek  prefixes.  The  chief  difficulty, 
however,  was  the  lack  of  secondary  standards,  which  were  to 
have  been  constructed  and  distributed  at  the  expense  of  the  State. 
Accordingly,  it  was  necessary  to  repeal  such  legislation,  as  the 
expense  involved  was  much  greater  than  the  government  could 
afford.  Moreover,  the  temporary  office  or  agency  of  weights  and 
measures  had  been  abolished  too  early  to  give  the  much-needed 
assistance  in  accustoming  the  people  to  the  use  of  the  new 
system.  There  was  also  embarrassment,  due  to  the  fact  that, 
previous  to  March  15,  1790,  there  had  been  public  scales  where 
the  people  could  weigh  their  merchandise.  These  institutions, 
which  had  been  done  away  with  by  law,  it  became  necessary  to 
re-establish,  and  this  was  done  for  cities  of  over  5000  inhabitants 
by  the  Act  of  27  Brumaire,  year  VII.  (November  17,  1798),  and 
subsequently  for  such  other  cities  as  was  necessary. 
Ff^In  the  meantime,  there  were  not  only  officials  for  weighing 
'  and  measuring,  but  also  private  individuals  who  carried  on  a 
similar  business,  and  were  ready  to  employ  the  old  as  well  as  the 
new  and  legal  measures.  As  a  result,  serious  abuses  and  frauds 
prevailed,  and  the  general  appreciation  of  the  merits  of  the  new 
system  was  decidedly  lukewarm.  Nevertheless,  it  made  progress, 
and  was  early  adopted  for  all  scientific  works  and  papers 
published  by  the  Institute  to  the  exclusion  of  all  other  systems. 
The  growth,  however,  was  not  as  much  among  the  citizens  at 
large  as  among  the  government  officials  and  scientific  men.  The 
reasons  given  were  chiefly  that  both  names  and  values  were 


DEVELOPMENT   OF  THE   METRIC   SYSTEM       65 

changed,  that  foreign  names  and  words  were  employed,  that  the 
names  were  too  long,  and  that  the  old  weights  and  measures  were 
persistently  used  in  bills  and  accounts.  To  answer  these 
objections,  but  with  the  result  of  complicating  matters  further,  a 
decree  was  issued  13  Brumaire,  year  IX.  (November  4,  1800), 
which  stated  that  the  decimal  system  of  weights  and  measures 
would  definitely  be  put  into  execution  for  the  entire  republic 
beginning  1  Vende"miaire,  year  X.,  and,  in  order  to  facilitate  its 
use,  the  names  given  to  weights  and  measures  in  public  documents, 
as  in  customary  usage,  should  be  explained  by  French  names  as 
given  in  a  list,  which  to  a  certain  extent  corresponded  to  the  simple 
nomenclature  tentatively  submitted  by  the  committee  of  the 
Academy  of  Sciences  in  1793.  There  was  to  be  no  synonym  for 
the  meter,  and  every  measure  to  which  a  public  denomination 
was  assigned  must  be  a  decimal  multiple  or  subdivision  of  that 
unit.  For  the  measurement  of  cloth  the  meter,  with  its  tenth 
and  hundredth  divisions,  was  to  be  employed,  while  the  term 
stere  was  to  be  used  still  as  a  measure  of  firewood  and  as  a 
solid  measure,  a  tenth  part  of  this  measure  being  adopted  for 
carpentry  and  known  as  a  solive.  The  decree  also  provided  that 
the  new  names  should  be  inscribed  on  the  weights  already 
constructed,  and  that  either  one  system  or  the  other  must  be 
employed. 

While  this  action  tended  to  weaken  the  integrity  of  the  metric 
system,  yet  it  preserved  its  fundamental  feature  of  decimal 
division,  but  it  was  followed  by  a  decree  of  Napoleon  of  February 
12,  1812,  which  had  a  most  serious  effect  on  the  work  already 
accomplished,  and  threatened  its  very  existence.  Despite  the 
objections  of  Laplace  and  other  scientists,  a  system  of  measures 
termed  "  usuelle  "  was  established  in  which  the  metric  system  was 
employed  as  the  basis,  but  which  made  use  of  such  multiples  and 
fractions  as  would  bring  about  measures  that  would  harmonize 
with  those  long  established  by  the  usage  of  commerce  and  of  the 
people  generally.  The  space  of  ten  years  was  fixed  for  a  period 
during  which  actual  experience  might  occasion  further  needs  of 
further  changes  in  weights  and  measures.  The  legal  or  metric 
system  was  to  be  taught  in  all  the  schools/including  the  primary 
schools,  and  was  to  be  employed  in  all  official  transactions, 
markets,  etc.  To  carry  out  the  provisious  of  this  decree  an 


66       EVOLUTION   OF   WEIGHTS   AND   MEASURES 

elaborate  series  of  rules  were  published  by  Montalivet,  Minister 
of  the  Interior,  March  28,  1812. 

The  "usiwlle"  measures  were  all  defined  in  terms  of  the 
metric  system,  and  there  were  included  a  large  number  corre- 
sponding to  those  in  daily  use.  Thus  the  toise  was  the  length  of 
two  meters,  and  was  divided  into  six  feet,  each  of  which  was 
defined  as  one-third  of  a  meter.  The  foot,  in  turn,  was  divided 
into  12  inches,  and  each  inch  into  12  lignes.  For  the  measure- 
ment of  cloth  and  fabrics  there  was  an  aune,  equal  to  12  deci- 
meters, divided  into  halves,  quarters,  and  sixteenths,  and  also- 
into  thirds,  sixths,  and  twelfths.  These  divisions  for  toise  and 
aune  were  to  be  marked  along  one  face  of  the  scale  or  measure,, 
while  the  other  must  have  the  regular  metric  divisions  on 
the  decimal  basis.  Various  weights  and  measures  for  retail 
business  were  provided  and  defined,  in  which  the  subdivision  was 
by  halves  or  some  other  non- decimal  factor  not  always  the  same. 
Thus,  for  the  measure  of  capacity,  such  as  grain,  there  was  the 
boisseau,  defined  as  ^  of  a  hectoliter,  with  a  double,  half,  and 
quarter  boisseau.  The  liter  also  was  divided  into  halves,  quarters,, 
and  eighths,  and  the  shape  and  material  of  measures  for  various 
liquids  was  specified.  The  livre  or  pound  was  defined  as  equal 
to  500  grams  or  a  half  kilogram,  and  was  divided  into  16  ounces 
of  8  gros  each.  Provision  was  made  for  the  verification  and 
sealing  of  weights  and  measures  by  a  government  bureau,  and 
also  for  the  construction  and  distribution  of  secondary  standards 
to  the  various  departments. 

The  use  of  measures  other  than  the  legal  ones  and  those 
specified  in  the  decree  was  forbidden  as  contrary  to  law.  The- 
legal  system  was  still  to  be  employed  in  all  government  works, 
officially  and  in  commerce,  and  it  was  explained  that  the  decree 
was  designed  only  to  affect  retail  business  and  the  small  trading 
of  daily  life.  All  formal  notices  must  be  expressed  in  legal 
measures  rather  than  in  those  tolerated,  and  the  legal  system 
was  to  be  taught  in  the  public  schools,  including  the  primary 
schools,  in  its  completeness.  This  law  was  in  force  until 
1837,  and  its  results  were  most  unsatisfactory,  since  it  simply 
added  to  the  confusion  by  increasing  the  number  of  weights, 
and  measures.  As,  in  any  event,  it  was  necessary  to  wait 
until  the  people  at  large  gradually  abandoned  the  old  measures. 


DEVELOPMENT   OF  THE   METRIC   SYSTEM        67 

it  served  no  useful  purpose  in  the  transition  period  to  add 
new  measures  that  essentially  were  neither  new  nor  old. 
The  prejudice  of  the  people  was  slowly  overcome,  however, 
and  the  instruction  given  in  the  schools  gradually  had  its 
effect.  From  government  use  and  general  commerce  the  use 
of  the  legal  system  extended  slowly  among  retail  dealers  and 
small  consumers. 

After  an  experience  of  a  quarter  of  a  century  with  theT^ 
itsuelle  measures,  it  was  thought  that  the  time  had  arrived  to  use  \ 
the  metric  system  exclusively,  and  an  attempt  to  that  end  was  ; 
made  in  a  bill  presented  in  the  House  of  Deputies,  February  28,  '. 
1837.  The  matter  was  vigorously  discussed  in  the  chamber,  and 
was  considered  by  several  committees,  by  whom  a  plan  for 
suita-ble  legislation  was  proposed.  Attention  was  called  to  the 
survival  of  the  old  measures  and  their  general  use,  and  to  the 
fact  that  the  mesures  usuelles,  while  they  had  contributed  much 
to  increasing  the  use  of  the  metric  system,  nevertheless,  being 
founded  on  the  measures  of  Paris,  were  not  particularly  useful 
where  these  measures  had  not  been  previously  employed,  as 
was  the  case  in  certain  parts  of  the  realm.  A  general 
discussion  of  nomenclature,  systems  of  division,  etc.,  took  place, 
but  the  advocates  of  the  metric  system  were  most  earnest  in 
resisting  any  modifications,  and  it  was  argued  that  the  yield- 
ing to  prejudice  manifested  in  the  legislation  of  1812  had 
been  a  serious  mistake.  It  was  also  urged  that  people  forced 
to  employ  the  new  system,  in  order  to  sell  their  goods,  would 
soon  learn,  and  that  no  new  measures  should  be  constructed 
whose  contents  were  not  in  exact  accord  with  the  metric  system. 
Accordingly,  after  considerable  discussion,  the  following  Act  was 
passed  by  the  Chamber  of  Peers  and  the  Chamber  of  Deputies, 
and  was  promulgated  July  4,  1837. 

Article  I. — The  decree  of  February  12,  1812,  concerning  weights 
and  measures,  is  hereby  repealed. 

Article  II. — The  use  of  instruments  for  weighing  and  mea- 
suring, constructed  in  accordance  with  Articles  II.  and  III. 
of  said  decree,  shall  be  permitted  until  January  1,  1840. 

Article  III. — After  January  1,  1840,  all  weights  and  measures, 
other  than  the  weights  and  measures  established  by  the  laws  of 
18  Germinal,  year  III.,  and  19  Frimaire,  year  VIII.,  constituting 


68       EVOLUTION   OF  WEIGHTS   AND   MEASURES 

the  decimal  metric  system,  shall  be  forbidden,  under  the  penalties 
provided  by  article  470  of  the  Penal  Code. 

Article  IV. — Those  possessing  weights  and  measures,  other 
than  the  weights  and  measures  above  recognized,  in  their  ware- 
houses, shops,  workshops,  places  of  business,  or  in  their  markets, 
fairs,  or  emporiums,  shall  be  punished  in  the  same  manner  as 
those  who  use  them,  according  to  article  479  of  the  Penal  Code. 

Article  V. — Beginning  at  this  same  date  all  denominations 
of  weights  and  measures  other  than  those  given  in  the  table 
annexed  to  the  present  law,  and  established  by  the  law  of  the 
18  Germinal,  year  III.,  are  forbidden  in  public  acts,  documents, 
and  announcements.  They  are  likewise  forbidden  in  acts  under 
private  seal,  commercial  accounts,  and  other  private  legal  docu- 
ments. Public  officers  violating  this  law  are  subject  to  a  fine 
of  20  francs,  which  shall  be  collected  compulsorily  as  in  a  matter 
of  registration.  The  fine  shall  be  10  francs  for  other  violators, 
and  shall  be  imposed  for  every  single  act  or  writing  under 
private  signature,  but  in  commercial  accounts  there  shall  be  only 
one  fine  for  every  case  in  which  the  prohibited  terms  are  used. 

Article  VI. — Judges  and  arbitrators  are  forbidden  to  render 
any  judgment  or  decision  in  favor  of  any  particular  items  in 
the  accounts  or  writings  in  which  the  denominations  forbidden 
by  the  preceding  article  shall  have  been  inserted  until  the  fines 
provided  by  the  preceding  article  shall  have  been  paid. 

Article  VII. — The  inspectors  of  weights  and  measures  shall 
discover  violations  provided  for  by  the  laws  and  rules  concerning 
the  metric  system  of  weights  and  measures.  They  may  proceed 
to  seize  weights  and  instruments  whose  use  has  been  prohibited 
by  the  said  laws  and  rules.  Their  testimony  in  a  court  of 
justice  shall  be  considered  as  direct  proof.  The  inspectors  will 
take  oath  before  the  tribunal  of  the  arrondissement. 

Article  VIII. — A  royal  ordinance  shall  regulate  the  manner 
in  which  the  inspection  of  weights  and  measures  shall  be 
accomplished. 

As  the  metric  system  gradually  became  firmly  established 
in  France,  the  French  Government,  through  diplomatic  channels, 
called  attention  of  the  various  nations  to  its  many  advantages, 
and,  at  the  same  time,  distributed  a  number  of  copies  of  the 
Meter  of  the  Archives,  which  had  been  prepared  at  the  Con- 


DEVELOPMENT   OF   THE   METRIC   SYSTEM        69 

servatoire  des  Arts  et  Metiers,  where  now  the  work  of  preparing 
standards  and  of  carrying  on  other  operations  in  connection  with 
the  weights  and  measures  took  place.  For  this  bureau,  a  new 
comparator,  capable  of  exact  measurement  and  facilitating  the 
operation  of  comparison,  had  been  constructed  by  Gambey,  and  it 
enabled  a  large  number  of  accurate  standards  to  be  prepared  for 
commercial  and  industrial  use,  though  in  most  cases  no  remark- 
able degree  of  precision  was  obtained.  Important  work,  however, 
was  done  in  the  study  of  platinum  standards  of  the  meter  for  the 
Prussian  Government,  preparatory  to  the  general  adoption  by 
that  country,  of  the  metric  system.  This  work  was  carried 
on  by  Eegnault,  Le  Verrier,  Morin,  and  Brix.1 

With  the  growing  use  of  the  metric  system  for  scientific  work, 
not  only  in  France,  but  throughout  Europe,  the  importance  of 
the  accuracy  of  its  fundamental  units  became  a  matter  of 
interest  to  mathematicians  and  geodesists  in  several  countries. 
Increased  activity  in  geodesy  had  brought  about  a  number  of 
measurements  of  arcs  of  meridian,  and  with  the  resulting  data 
it  became  possible  to  compute  anew  the  shape  of  the  earth 
and  the  length  of  the  quadrant.  Any  change  in  this  last  quantity, 
of  course,  affected  the  length  of  the  meter  as  the  fundamental 
unit  of  length,  and  called  it  into  question  as  an  absolute  and 
natural  standard.  That  such  was  the  case  was  early  demon- 
strated by  Bessel,2  while  General  T.  F.  De  Schubert  of  the 
Eussian  Army,  Colonel  George  Everest  of  the  British  Army,  and 
Captain  A.  E.  Clarke  of  the  British  Ordnance  Survey,  made 
geodetic  measurements  and  studies,  which  enabled  them  more 
accurately  to  determine  the  shape  of  the  earth.  As  a  result  of 
this  work,  it  was  found  impossible  to  depend  upon  the  accuracy 
of  the  determination  of  the  measurement  of  the  quadrant  of  a 
great  circle,  as  it  would  vary  in  different  places,  and  required 
a  most  exact  knowledge  of  the  shape  of  the  earth. 

These  questions,  it  must  be  remembered,  were  purely  scientific, 
and  did  not  influence  the  practical  development  of  the  system 


De    la    Precision     dans     la     Determination     des    Longueurs    en 
Metrologie,"  Rapports  Congr&s  International  de  Physique,  Tome  1,  1900,  p.  45. 

2  "  Ueber  einen  Fehler  in  der  Berechnung  der  Franzosischen  Gradmessuiig  und 
seinen  Einfluss  auf  die  Bestimmung  der  Figur  der  Erde,"  Schum.  Ast. 
Nachrichten,  1844,  vol.  xix.  No.  438,  pp.  98-1160. 


70       EVOLUTION   OF   WEIGHTS   AND   MEASURES 

either  in  France  or  abroad,  but  they  provoked  much  discussion 
among  scientific  men.  With  the  series  of  world's  expositions, 
which  began  with  that  at  London  in  1851,  an  opportunity  was 
given  to  the  people  at  large  to  examine  and  appreciate  the 
benefits  of  an  international  system  of  measures,  while  statistical 
and  scientific  congresses  saw  the  advantages  resulting  from  the 
use  of  uniform  weights  and  measures.  Important  among  these 
was  a  convention  formed  largely  of  the  official  delegates  to  the 
Paris  Exposition  of  1867,  which  adopted  a  series  of  resolutions  in 
which  the  superiority  of  the  metric  system  of  weights  and 
\measures  was  conceded,  the  benefits  of  uniformity  stated,  and  its 
/adoption  by  the  civilized  world  urged.  Furthermore,  the  con- 
vention deemed  it  advisable  to  advocate  the  study  of  the  metric 
system  in  the  public  schools,  and  to  recommend  its  use  for 
scientific  publications,  public  statistics,  postal  service,  in  customs, 
and  in  all  works  carried  on  by  the  governments. 

In  the  same  year  the  International  Geodetic  Association,  com- 
posed of  delegates  from  the  leading  countries  of  Europe,  met  at 
Berlin,  and  was  engaged  in  the  discussion  of  topics  of  great 
concern  to  all  interested  in  scientific  measurement.  Inasmuch  as 
many  of  the  standards  of  length  used  for  base  measurements  were 
all  end  standards,1  which  doubtless  had  become  worn,  or  possibly 
were  inexact,  these  geodesists  considered  it  of  the  utmost  import- 
ance that  there  should  be  new  and  common  standards  as  abso- 
lutely correct  as  then  existing  conditions  of  metrological  science 
could  make  them.  This  having  been  done  all  base  measurements 
could  be  referred  to  the  same  linear  standard,  thus  insuring  that 
all  European  geodetic  work  could  be  comparable,  and  could  be 
reduced  so  that  a  degree  of  a  great  circle  of  the  earth  could 
be  determined  with  accuracy  from  a  number  of  different  measure- 
ments. yThis  convention  decided  that  the  interests  of  science  in 
general,  and  of  geodesy  in  particular,  demanded  a  uniform  decimal 
system  of  weights  and  measures  throughout  Europe,  and  recom- 
mended the  adoption  of  the  metric  system  without  essential 

change,/and   especially  without   the  metric   foot.2     In   order  to 

/ 

1  There  were  by  this  time  a  few  geodetic  line  standards,  among  others  those  of 
Spain,  Egypt,  and  probably  that  of  Clarke. 

2Bericht  iiber  die  Verhandlungen  der  von  30  September  bis  7  Octobre,  1867,  zu 
Berlin  abgehaltenen  allgemeinen  Conferenz  der  Europaischen  Gradmessung,  Berlin, 
1868,  p.  126. 


DEVELOPMENT   OF   THE   METRIC   SYSTEM        71 

secure  such  a  uniformity  of  measures  the  convention  decided  in 
favor  of  the  construction  of  a  new  European  prototype  meter 
differing  in  length  as  little  as  possible  from  the  Meter  of  the 
Archives  at  Paris,  and  compared  with  it  to  the  highest  degree  of 
accuracy  possible.  In  its  construction  there  would  be  observed 
all  refinements  secured  by  the  advance  of  metrological  science, 
and  especially  there  would  be  considered  its  availability  for 
comparisons  with  secondary  standards  of  length.  The  con- 
struction of  the  new  standard  was  to  be  undertaken  by  an 
international  commission  appointed  by  the  respective  governments, 
and  the  desirability  of  establishing  an  international  bureau  of 
weights  and  measures  was  expressed.  Thus  the  metric  system 
came  to  be  recognized  as  something  of  international  concern,  and 
its  preservation  and  improvement  a  matter  that  concerned  the 
world  at  large  as  well  as  France. 

The  action  of  the  Association  G-eode'sique  was  echoed  by  the 
St.  Petersburg  Academy  of  Sciences,  and  this  body  expressed  the 
interest  of  the  scientific  world  at  large  in  a  proper  standard  of 
mass,  as  well  as  a  new  standard  of  length,  in  a  communication  to 
the  Paris  Academy  of  Sciences  in  1869,  in  which  iShey  suggested 
taking  common  steps  Nt°wards  the  establishment  of  an  inter- 
national metric  system.  This  proposition  was  not  enthusiastically 
received  in  France,  where  many  of  the  scientific  men  thought 
that  the  meter  and  the  kilogram  were  the  work  of  French 
savants,  and  looked  upon  them  as  something  that  should  not  be 
tampered  with,  especially  by  alien  scientists ;  but  those  more 
especially  interested  in  metrology  perceived  that  the  application 
of  recent  advances  in  the  theory  and  practice  of  the  science  of 
weighing  and  measuring  was  desirable,  and  that  new  standards 
could  be  constructed  with  profit,  provided  that  the  original 
.standards  should  remain  as  the  underlying  basis  of  the  system. 
Accordingly,  on  the  representation  of  the  Paris  Academy  of 
Sciences,  the  French  Government  took  up  the  matter,  and  after 
.an  examination  of  the  question  in  its  different  aspects  by  a 
•committee  consisting  of  representatives  from  the  Academy  of 
Sciences  and  the  Bureau  of  Longitude,  a  report  was  made  in 
favor  of  the  proposed  plan,  and  the  Minister  of  Agriculture  and 
Commerce  (Alfred  Leroux)  brought  the  matter  to  the  attention 
vof  the  Emperor,  Napoleon  III.,  in  a  long  and  comprehensive 


72       EVOLUTION   OF   WEIGHTS   AND   MEASURES 

statement,  dated  September  1,  1869,  favoring  the  calling  of  an 
international  conference.1 

This  report  was  approved  by  the  Emperor,  and  the  French 
Government  communicated  through  diplomatic  channels  with  the 
various  nations,  inviting  them  to  send  delegates  to  a  conference 
to  be  held  at  Paris  to  discuss  the  construction  of  a  new  prototype 
meter  as  well  as  a  number  of  identical  standards  for  the  various- 
participating  nations.  This  action  was  especially  important  as 
emphasizing  the  international  character  of  the  system  by  allowing 
the  participation  of  a  number  of  nations  in  the  construction  of  a 
standard  that  would  serve  for  all,  France  included.  It  was  also 
an  admission  on  the  part  of  the  French  Government  that  a  new 
(line)  standard  (m&tre  a  trait)  was  necessary,  and  that  every 
means  should  be  taken  to  conserve  the  metric  system  by  putting 
its  standards  on  a  permanent  basis. 

The  invitation  was  accepted  by  the  nations  to  which  it  was 
extended,  and  in  August,  1870,  delegates  from  twenty-four  States 
met  at  Paris.  In  the  meantime,  in  order  to  make  suitable 
preparations,  and  to  lighten  the  work  of  the  International  Com- 
mission as  much  as  possible,  the  French  members  had  assembled, 
and  since  September  1st,  1869,  had  been  actively  engaged  in 
studying  the  subject,  especially  on  its  scientific  side,  and  preparing 
a  working  basis  for  the  conference.2  Owing  to  the  breaking  out 
of  the  war  between  Germany  and  France  this  session  was  of 
short  duration,  but  it  was  decided  that  instead  of  a  single  new 
standard  a  number  of  identical  standards  should  be  constructed 
for  the  nations  participating  in  the  convention,  and  that  one  of 
the  number  should  be  chosen  as  the  international  standard,  and 
should  be  deposited  in  some  convenient  place  accessible  to  all  the 
participating  countries,  and  under  their  common  care. 

Summoned  anew  by  the  French  Government,  the  International! 
Commission  met  under  more  peaceful  auspices  at  Paris,  on  Sep- 
tember 24,  1872,  thirty  States  being  represented  by  fifty-one 
delegates,  among  whom  were  included  many  distinguished 
scientists,  and,  as  was  natural,  the  foremost  metrologists  of  the 
world.  By  reason  of  the  previous  session,  and  the  activity  of 
the  French  committee  in  the  interval  that  had  elapsed,  the 
work  of  the  Commission  was  very  clearly  mapped  out,  and 

^igourdan,  Le  Systeme  Mttrique  (Paris,  1901),  pp.  265-272.          2  Ibid.  p.  273. 


DEVELOPMENT   OF   THE   METRIC   SYSTEM        73 

little  time  was  spent  in  mere  preliminary  discussion.  The  first 
and  most  important  announcement  was  the  report  of  the  French 
Committee,  that  after  a  careful  examination  had  been  made  of 
the  standards  of  the  Archives,  the  Meter  was  found  in  a 
very  satisfactory  state  of  preservation,  and  in  such  condition 
as  to  inspire  all  confidence  in  any  operations  for  which  it  might 
serve  as  a  base.  Likewise,  the  Kilogram  of  the  Archives  also- 
was  found  to  be  perfectly  preserved.  Comparisons  which  were 
effected  between  the  prototype  meter  and  its  contemporaries  of 
the  Conservatory  and  the  Observatory  demonstrated  that  the 
Meter  of  the  Archives  had  not  appreciably  altered  in  length.1 

The  Commission  was  divided  into  eleven  committees  composed 
of  delegates  specially  qualified  for  the  separate  branches  of  the- 
work,  and  the  subjects  assigned  to  each  committee  were  as  follows: 
Study  of  the  ends  of  the  meter  of  the  Archives,  material  for  the- 
new  meter,  its  form  and  method  of  support,  thermornetry  and 
expansion,  normal  temperature  of  the  meter  and  kilogram,  weights- 
in  vacuum  or  in  air,  comparator,  creation  of  an  international  bureau 
of  weights  and  measures,  weight  of  a  cubic  decimeter  of  water, 
material  and  form  of  the  standard  kilogram,  balances  and 
methods  of  weighing,  and  preservation  of  the  standards  and 
providing  for  their  invariability. 

Addressing  themselves  to  the  consideration  of  these  topics,  thi\ 
commission  speedily  reached  satisfactory  conclusions,  and  specific-j 
resolutions  were  adopted  outlining  the  plans  to  be  followed  and' 
the  direct  decisions  which  the  Commission  had  arrived  at.2 

These  resolutions  were  in  substance  as  follows  :  The  M&tre  des. 
Archives  was  to  be  the  point  of  departure,  and  was  to  be  repro- 
duced by  a  m&tre  a  traits  (line  standard),  it  having  been  found 
that  the  ends  of  the  platinum  bar  of  the  historic  meter  were 
sufficiently  well  preserved  to  warrant  employing  it  as  an  original 
standard.  This  last  matter,  however,  would  be  finally  determined 
when  the  actual  work  of  comparison  had  commenced.  The- 
identical  copies  of  the  standard  meter  to  be  furnished  to  each  of 

1  Bigourdan,  Le  Syst&me  Mdtrique,  p.  274. 

2  For  complete  text  of  resolutions  and  discussion,  see  Bigourdan,  Le  Systeme 
M&rique,  pages  299-313.     A  translation  of  the  same  will  be  found  pages  52-55, 
"  Report  of  the  Committee  on  Coinage,  Weights  and  Measures,"  of  the  House  of 
Representatives,  46th  Congress,  first  Session,  Report  14,  1879. 


74       EVOLUTION   OF   WEIGHTS   AND   MEASURES 

the  countries  were  to  be  metres  a  traits,  but  at  the  same  time  a 
number  of  end  standards  (metres  a  bouts)  whose  equations  would 
also  be  determined,  would  bs  constructed  for  such  countries  as 
•specially  desired  them.  The  new  standards  were  to  represent 
the  length  of  a  meter  at  0  degree  centigrade,  and  the  material 
was  to  be  an  alloy  of  platinum  90  per  cent,  and  iridium  10  per 
cent.,  with  a  tolerance  of  2  per  cent,  either  in  excess  or  defici- 
ency. The  measuring  bars  were  to  be  constructed  from  a  single 
ingot  produced  at  one  casting  and  carefully  annealed.  Their 
length  in  the  case  of  the  metres  a  traits  was  to  be  102  centi- 
meters, and  their  cross  section  was  carefully  designed  according 
to  specification  by  Tresca.1  Detailed  instructions  were  also 
adopted  for  the  determining  of  the  expansion,  the  marking,  and 
the  calculation  of  the  equations  of  the  different  standards.  The 
.action  of  the  Commission  in  reference  to  the  kilogram  was  as 
follows  (Section  xxii.) :  "  Considering  that  the  simple  relation 
which  was  established  by  the  originators  of  the  metric  system 
between  the  unit  of  weight  and  the  unit  of  volume  is  represented 
by  the  actual  kilogram  in  a  manner  sufficiently  exact  for  the 
ordinary  uses  of  industry  and  of  commerce,  and  even  for  most 
of  the  ordinary  requirements  of  science  ;  considering  also  that  the 
•exact  sciences  have  not  the  same  need  of  a  simple  numerical 
relation,  but  only  of  a  determination  of  such  relation  as  perfect  as 
possible ;  and  considering  the  difficulties  that  would  arise  from  a 
•change  in  the  actual  unit  of  the  metric  system,  it  is  decided  that 
the  international  kilogram  shall  be  derived  from  the  kilogramme 
des  Archives  in  its  actual  state/'  The  international  kilogram  was 
to  be  determined  with  reference  to  its  weight  in  a  vacuum,  and 
the  material  of  the  standards  was  to  be  the  same  alloy  of 
platinum-iridium  as  was  employed  for  the  standard  meters.  In 
form  the  international  kilograms  were  to  resemble  the  Kilo- 
gram of  the  Archives,  being  cylindrical,  with  height  equal  to 
the  diameter,  and  with  the  edges  slightly  rounded.  It  was  also 
decided  that  the  determination  of  the  weight  of  a  cubic  decimeter 
of  water  should  be  made  by  the  Commission,  and  that  a  new 
balance  of  extreme  precision  should  be  constructed  and  employed. 
The  method  of  weighing  and  determining  the  volume  of  the 
kilograms  was  outlined,  but  it  was  decided  that,  as  also  in  the 

JSee  chapter  x.,  p.  254. 


DEVELOPMENT   OF   THE   METRIC   SYSTEM        75 

case  of  the  metre  des  Archives,  the  kilogramme  des  Archives  should 
not  be  placed  in  a  liquid  until  the  end  of  the  operations. 

The  plan  for  actually  carrying  out  the  work  of  the  Commis- 
sion involved  the  construction  of  as  many  identical  standard 
meters  and  kilograms  as  were  needed  by  the  countries  interested, 
all  of  which  should  be  made  and  compared  by  the  Commission, 
and  required  that  a  standard  meter  and  a  standard  kilogram 
should  be  selected  as  international  prototype  standards  in  terms 
of  which  the  equations  of  all  the  others  should  be  expressed. 
The  actual  construction  of  these  new  standards,  the  tracing  of 
the  defining  lines,  and  the  comparison  with  the  standards  of  the 
Archives,  were  entrusted  to  the  French  section  of  the  Commission, 
which  was  to  perform  the  work  with  the  concurrence  and  under 
the  general  direction  of  a  permanent  committee  of  twelve  mem- 
bers duly  appointed  to  have  general  supervision  of  the  work. 

The  Commission  also  advocated  the  founding  of  an  inter-^i 
national  bureau  of  weights  and  measures,  to  be  located  at  Paris, 
which  would  be  both  international  and  neutral,  and  supported  by 
the  common  contributions  from  the  nations  party  to  a  treaty 
creating  such  an  establishment.  It  was  proposed  that  it  should 
be  under  the  supervision  of  the  permanent  committee  of  the 
International  Metric  Commission,  and  should  be  used  for  the 
comparison  and  verification  of  the  new  metric  standards,  for 
the  custody  and  preservation  of  the  new  prototype  standards,  and 
for  such  other  appropriate  comparisons  of  weights  and  measures 
.as  might  come  before  it  in  proper  course.  In  accordance  with 
the  suggestions  of  the  Commission,  the  French  Government  again 
•communicated  diplomatically  with  the  various  governments  rela- 
tive to  the  establishment  of  such  a  bureau,  and  the  reports  of 
the  various  delegates  having  in  the  meantime  been  made,  and  the 
project  in  all  its  details  thoroughly  understood,  on  May  20,  1875, 
.a  treaty  was  concluded  at  Paris,  in  which  the  recommendations 
of  the  Commission  were  put  into  effect.1  This  treaty  was  duly 
.signed  by  accredited  representatives  of  the  following  countries : 
United  States,  Germany,  Austria-Hungary,  Belgium,  Brazil,2 

lSee  Bigourdan,  Le  Systeme  M&riqtte,  pp.  328-337.  U.S.  House  Representa- 
tives, Committee  on  Coinage,  Weights  and  Measures,  46th  Congress,  1st  Session, 
Heport  No.  14,  pp.  43-50. 

2  Brazil  did  not  ratify  the  treaty. 


76       EVOLUTION   OF  WEIGHTS  AND   MEASURES 

Argentine  Confederation,  Denmark,  Spain,  France,  Italy,  Peru, 
Portugal,  Kussia,  Sweden  and  Norway,  Switzerland,  Turkey,  and 
Venezuela.  Of  the  countries  present  at  the  conferences,  Great 
Britain  and  Holland  declined  to  participate  in  the  treaty  or  to 
contribute  to  the  expense  of  an  international  establishment  for 
the  metric  system.  The  British  Government,  in  explanation  of 
this  action,  stated  that  they  could  not  recommend  to  Parliament 
any  expenditure  in  connection  with  the  metric  system,  inasmuch 
as  it  was  not  legalized  in  that  country,  nor  could  it  support  a 
permanent  institution  established  in  a  foreign  country  for  its 
encouragement.  A  change  of  feeling,  however,  took  place  in 
England,  and  in  September,  1884,  Great  Britain  joined  the 
Convention.  With  the  treaty  were  signed  at  the  same  time  a 
series  of  regulations  for  the  newly  created  bureau,  and  a  set 
of  temporary  or  transient  provisions  referring  to  the  work  already 
in  hand  which  had  been  undertaken  by  the  French  section  under 
the  direction  of  the  conference  of  1872. 

The  treaty  provided  for  the  establishment  and  maintenance, 
at  the  joint  charge  of  the  contracting  parties,  of  a  scientific 
and  permanent  international  bureau  of  weights  and  measures,  to 
be  located  at  or  near  Paris,  in  a  territory  to  be  kept  strictly 
neutral.  The  bureau  was  to  be  installed  in  a  special  building, 
supplied  with  the  necessary  instruments  and  apparatus,  and  was 
to  be  conducted  by  an  international  committee,  composed  of 
fourteen  delegates,  each  from  a  different  country,  with  a  personal 
scientific  staff  of  a  director  with  assistants  and  workmen.  The 
first  duty  of  the  bureau  would  be  the  verification  of  the  new 
international  metric  standards  then  in  progress  of  construction, 
but,  in  addition,  it  would  have  such  permanent  functions  as  the 
custody  of  the  new  international  metric  prototypes,  all  future 
official  comparison  with  those  of  the  national  standards,  com- 
parisons with  the  metric  standards  of  other  units,  the  stan- 
dardizing of  geodetic  instruments  and  other  standards  and  scales 
of  precision,  and,  in  short,  to  undertake  such  scientific  work 
connected  with  metrology  as  would  be  possible  with  its  equip- 
ment, and  which  would  supply  the  greatest  benefits  to  the 
supporting  nations.  The  expense  of  the  new  establishment  was 
to  be  met  by  contributions  from  the  various  signatories  to  the 
convention,  on  the  basis  of  their  respective  population,  multiplied 


DEVELOPMENT   OF  THE   METRIC   SYSTEM        77 

by  the  factor  3  for  countries  where  the  metric  system  was 
obligatory,  by  2  where  it  was  legalized  but  not  obligatory,  and  by 
1  where  it  was  not  yet  legalized.1 

The  treaty  was  ratified  by  the  various  contracting  governments, 
and  the  international  committee  from  the  conference  of  1872  was 
continued  under  the  presidency  of  General  Ibanez  of  Spain,  and 
authorized  to  begin  the  preliminary  operations.  The  first 
question  was  to  find  a  suitable  location  for  the  laboratories  of 
the  bureau,  and  this  was  solved  by  the  offer  of  the  French 
Government  to  turn  over,  without  charge,  the  Pavilion  de  Breteuil, 
including  a  tract  of  land  about  two  and  a  half  hectars  in  extent, 
situated  on  the  bank  of  the  Seine  near  Sevres,  at  the  entrance 
of  the  Park  of  St.  Cloud.2  This  building,  which  is  on  a  hill, 
dates  back  to  the  time  of  Louis  XV.,  and  was  used  by  kings 
and  emperors  as  a  palace  and  place  of  resort,  especially  by 
Napoleon  I.,  who,  it  is  said,  was  at  times  wont  to  study  here. 
The  pavilion  itself  was  in  bad  repair,  having  been  damaged  in  the 
siege  of  Paris,  but  the  walls  were  in  good  condition,  and  it  was 
decided  to  put  the  building  in  order  to  be  used  for  the  offices  of 
the  bureau  and  the  residence  of  the  staff,  and  to  construct  a  new 
and  special  building  for  the  actual  scientific  work  and  for  the 
safe  keeping  of  the  international  prototypes.  The  latter  obser- 
vatoire  or  laboratory,  a  one-story  building,  was  completed  and 
the  apparatus  installed  from  1878,  and  has  been  in  constant  use 
ever  since.  Its  equipment  has  for  the  most  part  been  specially 
provided,  and  includes,  without  doubt,  the  most  complete  and 
accurate  instruments  of  precision  in  existence.  Each  of  these 
merits  a  complete  description,  which  is  of  course  not  possible 
in  these  pages,  but  some  of  the  essentials  of  the  more  im- 
portant instruments  will  be  found  described  in  the  chapter  on 
Standards.3 

The  construction  of  the  new  standards  involved  greater 
difficulties  than  had  been  anticipated.  The  French  section 
had  melted  an  ingot  of  the  platinum-indium  alloy  specified  by 
the  conference  of  1872,  but  it  was  found  to  contain  impurities 

1  It  has  recently  (1906)  been  proposed  by  the  Committee  to  drop  the  coefficients. 
'2For  description  see  Bigourdan,  Le  Systtme  Metrique  (Paris,  1901),  pp.  353-362. 
Ouillaume,  La  Convention  du  Metre  (Paris,  1902),  pp.  21-25. 
3  See  chapter  x. 


78       EVOLUTION   OF   WEIGHTS   AND   MEASURES 

in  the  form  of  slight  admixtures  of  rhodium,  ruthenium,  and 
iron.  This,  accordingly,  provoked  a  controversy,  which,  however, 
was  settled  by  obtaining  eventually  material  which  satisfied 
all  the  requirements. 

From  time  to  time,  as  occasion  demanded,1  the  International 
Committee  held  various  meetings  connected  with  the  maintenance 
and  operation  of  the  Bureau  International,  and  in  1887  a 
resolution  was  passed  defining  the  unit  of  mass  as  follows : 

"  The  mass  of  the  international  kilogram  is  taken  as  unity  for 
the  international  use  of  weights  and  measures." 2 

This  definition  enabled  a  more  perfect  statement  of  the  funda- 
mental basis  of  the  metric  system  to  be  made,  and  produced  an 
increased  exactness  which  was  most  desirable.  In  1889  a  second 
International  Conference  was  assembled,  which  passed  on  the 
work  of  the  International  Committee,  and  approved  the  standards- 
.which  were  submitted  for  their  examination,  together  with  a 
record  of  all  experiments  and  investigations  that  had  been  made 
in  their  preparation.  The  conference  definitely  adopted  the 
international  prototypes  of  the"  meter  and  of  the  kilogram  as  the 
standards  of  length  and  mass  respectively,  and  the  centigrade 
scale  of  the  hydrogen  thermometer  was  adopted  for  their 
definition  and  determination.  The  national  prototype  standards 
were  also  approved,  and  were  distributed  by  lot  to  the  various 
countries  contributing  to  the  Bureau,  and,  finally,  a  committee 
was  appointed  to  deposit  the  international  standards, — meter 
and  kilogram, — in  the  safe  of  the  vault  of  the  Observatory 
at  Breteuil  designed  for  their  reception,  and  this  was  accom- 
plished with  the  observance  of  all  due  formality, — the  various 
keys  of  the  apartment  being  distributed  to  different  officers,* 
whose  joint  presence  was  necessary  for  any  examination  of  the 
standards. 

Mention  might  properly  be  made  of  the  elaborate  scientific 
researches  carried  on  at  the  Bureau,  and  the  valuable  memoirs 4 

1  Formerly  every  year  ;  now  every  two  years. 

2  Proces-verbaux  du    Comite  International    de*   Poids  et   Memres  pour   1S87, 
p.   88. 

3  The  president  of  the  International  Committee,  the  director  of  the  French 
'Archives,  and  the  director  of  the  Bureau. 

4  See    Travaux  ei  M^moires   du   Bureau  International  des   Poids   et   Mesure* 
(Pafris,  1881—). 


DEVELOPMENT   OF  THE   METRIC   SYSTEM        79 

published  at  frequent  intervals  in  which  these  are  described. 
With  the  determination  of  the  prototype  standards  for  the  meter 
and  the  kilogram  accomplished,  many  other  problems  in  metrology, 
such  as  the  study  of  temperature  measurements,  the  determina- 
tion of  the  meter  in  terms  of  the  wave-length  of  light,  the 
construction  of  standards  for  electrical  measurements,  the  study 
of  alloys  for  standards,  especially  those  used  in  geodesy,  etc., 
have  received  attention  from  the  scientific  staff,  and  the  work 
accomplished  has  been  of  marked  and  permanent  value. 


CHAPTER    III. 
DEVELOPMENT  OF  THE   METRIC  SYSTEM  IN   EUROPE. 

WHILE  an  international  system  of  weights  and  measures  was 
•contemplated  by  the  French  scientists,  yet  in  the  formulation  of 
the  metric  system  comparatively  little  general  interest  was 
manifested  by  other  nations,  and  comparatively  little  aid  was 
given  by  their  scientific  men.  We  have  seen  how  an  international 
•commission  of  scientists  examined  and  approved  the  determination 
of  the  meter  and  kilogram,  and  the  important  parts  played  by 
Van  Swinden  and  Tralles  in  this  work  of  verification.1  These 
foreign  delegates  appreciated  the  advantages  of  the  new  system, 
as  did  other  men  of  science,  but  the  times  were  unpropitious  for 
innovations  which  would  unsettle  and  change  the  ordinary  habits 
.and  customs  of  the  people.  Inasmuch  as  France  was  at  war 
with  the  greater  part  of  Europe  during  the  opening  years  of  the 
nineteenth  century,  the  mere  mention  of  the  source  of  reforms  in 
weights  and  measures  was  in  many  instances  an  argument  against 
their  adoption.  Furthermore,  the  actual  governments  themselves 
were  changing  constantly  in  many  parts  of  Europe,  and  the 
struggle  for  territory  and  national  existence  was  of  more  im- 
mediate importance  than  such  minor  matters  as  those  concerning 
commerce  and  the  domestic  life  of  the  people.  Indeed,  had  the 
change  been  attempted  generally  at  this  time  it  would  hardly 
have  met  with  success ;  for,  as  we  have  seen  in  the  case  of  France, 
not  only  was  compulsory  legislation  eventually  necessary,  but  an 

1  The  names  of  nine  foreign  scientists  were  attached  to  the  documents  accom- 
panying the  standard  meter  and  kilogram  when  given  to  the  French  Government 
for  deposit  in  the  Archives. 


THE   METRIC   SYSTEM   IN   EUROPE  81 

able  and  active  administration  working  on  some  wise  and  per- 
manent plan  was  required  to  put  it  into  effect.  Consequently, 
before  any  general  consideration  of  adopting  the  new  system 
could  take  place,  it  was  necessary  that  there  should  be  perman- 
ence and  stability  in  the  various  governments. 

As  the  fixing  of  weights  and  measures  is  manifestly  an 
attribute  of  government,  so  any  successful  reforms  must  depend 
upon  the  character  and  strength  of  a  particular  government,  and 
in  order  to  influence  neighboring  countries  the  territory  affected 
should  be  comparatively  large  and  the  number  of  its  inhabitants 
considerable.  Consequently  the  adoption  of  the  metric  system, 
in  a  half-hearted  way,  by  a  petty  kingdom  here  and  a  principality 
there,  likely  at  any  time  either  to  be  absorbed  by  its  neighbors,  or 
to  conquer  and  to  rule  them,  would  and  did  have  little  influence 
on  the  general  ultimate  use  of  the  new  weights  and  measures. 
This,  however,  must  not  be  understood  as  implying  that  at  the 
beginning  of  the  nineteenth  century  there  was  no  need  for 
reforms  either  in  Europe  at  large  or  in  particular  states. 
Mediaeval  conditions  survived,  and  the  same  evils  that  prevailed 
in  France  were  experienced  throughout  Europe.  The  same  name 
was  applied  to  measures  whose  values  varied  considerably  not 
•only  in  different  states  but  even  in  different  cities  of  the  same 
state. /Lack  of  uniformity,  both  in  units  and  standards,  was 
universal,  with  the  natural  result  of  hindering  commerce  and  of 
generally  cheating  the  less  intelligent  party  to  any  transaction. 
True,  French  conquest  had  carried  with  it  the  metric  system,  but 
it  was  used  merely  under  compulsion,  and  so  7soon  as  there  was  a 
change  in  political  conditions  the  old  measures  we're  resumed. 
Aside  from  the  scientific  propaganda,  due  to  the  undisputed 
pre-eminence  of  French  workers  in  exact  and  applied  science, 
comparatively  little  could  be  done  towards  forcing  the  issue,  and 
the  adoption  of  the  metric  system  waited  largely  on  political 
circumstances  which  affected  the  life  and  commerce  of  the  people 
at  large,  and  which  were  duly  appreciated  by  statesmen.  These 
conditions  were  brought  about  by  the  decline  of  war,  and  the 
resulting  opportunity  for  the  people  to  turn  to  the  pursuits  of 
farming,  commerce,  and  manufacturing.  If  a  number  of  states  or 
cities  were  brought  into  closer  political  relations,  forming  a  larger 
state  or  possibly  a  confederation,  their  commercial  relations 

F 


82       EVOLUTION   OF   WEIGHTS   AND   MEASURES 

naturally  developed,  and  in  order  to  increase  the  wealth  and 
resources  of  the  state,  both  material  and  military,  it  was  essential 
that  the  government  should  take  such  measures  as  would  best 
stimulate  commerce  and  manufactures.  Accordingly,  it  was  early 
recognized  that  uniformity  of  weights  and  measures  within  the 
boundaries  of  a  state  not  only  contributed  but  was  essential  to 
the  welfare  of  its  inhabitants,  while,  furthermore,  its  foreign 
commerce  was  increased  by  having  the  same  weights  and 
measures  as  its  neighbors.  When  we  join  to  these  considerations- 
the  fact  that  the  separate  systems  in  nearly  all  cases  were 
illogical,  inconvenient,  and  lacking  in  uniformity  and  facility  of 
use,  we  have  the  explanation  of  the  eventual  spread  of  the  metric 
system  in  Europe. 

On  the  return  of  Tralles  from  Paris  he  endeavored  to  introduce 
into  Switzerland  the  metric  weights  and  measures,  and  on  March 
4th,  1801,  a  law  was  passed  adopting  these  measures  ;  but,  against 
his  advice,  special  names  were  given  to  the  various  measures. 
Likewise,  Van  Swinden,  after  his  return  to  Holland  from  Paris, 
attempted  to  bring  about  the  adoption  of  the  metric  weights  and 
measures  in  his  own  country,  and  in  1802  the  Corps  Legislatif 
decided  in  part  on  the  new  system.  Yet  so  many  features  were 
lacking  from  their  plan,  that  the  completeness  and  general 
availability  characteristic  of  the  system  were  much  impaired,  to 
the  great  regret  of  the  scientist.  No  record  has  been  found  to 
indicate  whether  the  law  was  repealed  or  never  came  into  effect, 
but  with  the  invasion  of  Holland  by  Napoleon,  a  decree  of 
January  11,  1811,  referred  the  weights  and  measures  of  that 
country  to  those  of  the  metric  system.1 

In  Milan,  in  1803,  the  meter  and  the  kilogram  were  adopted  as 
the  basis  of  a  series  of  measures  arranged  on  a  decimal  scale,  but 
new  and  local  names  were  given  to  them.  Thus  the  Iraccio,  as 
the  unit  of  length,  was  equivalent  to  the  meter,  while  the  kilogram 
was  known  as  a  libbra  metrica,  or  metric  pound.  In  Baden,  in 
1810,  apfund,  equal  to  one-half  of  the  kilogram,  was  adopted  as  the 
unit  of  weight,  and  was  decimally  subdivided.  The  unit  of  linear 
measure  was  the  ruthe,  which  was  equivalent  to  three  meters,. 

aBigourdan,  Le  Systeme  M&rique,  p.  241.  On  August  21,  1816,  a  law  was. 
enacted  establishing  the  metric  system,  and  later  additional  Acts  were  passed 
which  will  be  alluded  to  in  the  course  of  a  few  pages. 


THE   METRIC   SYSTEM   IN   EUROPE  83 

while  the  dry  and  liquid  measures  of  capacity  were  also  defined 
in  terms  of  the  French  metric  measures.  However,  subsequent 
legislation  was  required,  and  by  an  order  dated  August  21,  1828,  the 
new  measures  were  made  compulsory  with  the  year  1831.  Some- 
what similar  steps  were  taken  also  in  Hesse-Darmstadt  in  1821, 
the  pfund  and  the  shoppen  being  made  equal  to  one-half  a  kilogram 
and  one-half  a  liter  respectively,  while  the  fuss,  or  linear  unit,  was 
one-fourth  of  the  meter,  and  the  elle  four-fifths.  In  Switzerland, 
in  1828,  it  was  proposed  to  adopt  a  common  system  of  weights  and 
measures  for  the  various  cantons,  and  in  1835  twelve  of  these 
divisions  entered  into  an  agreement  known  as  the  "  Maass 
concordats,"  to  which  reference  will  be  made  later.  This  plan 
consisted  essentially  of  the  usual  measures  defined  in  terms  of  the 
metric  units. 

The  French  Government,  as  we  have  seen,  having  experienced 
difficulty  in  securing  the  exclusive  use  of  the  metric  system  by  its 
own  people  did  not  take  active  measures  towards  extending  its  use 
abroad  until  after  the  passage  of  the  law  of_J837,  which  rendered 
the_system  universal  and  compulsory  throughout  France.  In  1841 
the  Minister  of  Agriculture  and  Commerce,  Cunin-Gridaine,  con- 
sidered that  much  good  would  be  accomplished  by  the  exchange 
of  standards  of  weights  and  measures  between  France  and  the 
important  commercial  countries  of  the  world.  He  was  supported 
by  the  Minister  of  Foreign  Affairs,  Guizot,  who  arranged  for  such 
an  exchange  through  the  diplomatic  channels  of  the  various 
governments.1  Accordingly  these  standards  were  duly  sent,  and 
in  1853  the  United  States  received  a  complete  series  of  French 
standards,  which  included  a  steel  meter  that  had  been  compared 
with  the  platinum  standard  at  the  Conservatoire  des  Arts  et 
Metiers,  and  likewise  a  gilt  kilogram  whose  constants  had  been 
determined  in  terms  of  the  kilogram  of  the  Archives. 

The  beginjiing--of  a  general  feeling  in  .favor  of  the  universal 
adoption  of  a  single  system  of  weights  and  measures,  and  the 
Opinion  that  for  this  purpose  the  metric  system  was  the  most 
suitable,  may  be  considered  to  date  from  theLondon  Exposition 
of  186 17  to  which  reference  has  already  been  made.  Despite 
the  fact  that  metric  weights  and  measures  had  been  used,  and 
their  adoption  advocated  by  scientific  workers,  it  cannot  be  said 

1  Bigourdan,  Le  Systtme  Mttrique,  p.  245. 


84       EVOLUTION   OF   WEIGHTS   AND   MEASURES 

that  before  this  time  the  importance  of  the  subject  was  recognized 
generally,  and  that  economists  and  statesmen  had  thoroughly 
realized  the  benefits  that  would  ensue  from  a  single  and 
universal  system  of  weights  and  measures,  as  well  as  a  common 
and  universal  basis  for  coinage,  in  which  there  should  be  a 
single,  and  preferably  decimal,  principle  of  division.  But  from 
such  a  beginning  the  agitation  spread,  and  nearly  ever^jiation 
soon  had  a  group  of  earnest  advocates  of  the  metric  system, 
which  included  not  only  such  scientific  men  as  chemists, 
physicists,  astronomers,  and  engineers,  not  to  mention  economists 
and  statisticians,  but  also  merchants  and  manufacturers.  This 
was  due  to  the  bringing  together  from  many  quarters  of  the 
globe  of  a  large  number  of  representative  merchants,  producers, 
and  manufacturers,  with  their  various  wares  and  products,  and 
also  scientific  men  and  others  who  were  called  to  pass  upon  the 
comparative  merits  of  the  various  articles  on  exhibition.  At 
the  conclusion  of  the  London  Exposition,  the  Society  of  Arts, 
in  a  communication  addressed  to  the  Lords  of  the  Treasury,  asked 
if  it  were  not  possible  that  some  arrangement  could  be  made 
whereby  a  universal  decimal  system  of  moneys,  weights,  and 
measures  could  be  adopted  in  common  for  all  the  nations  of  the 
world.  This  was  possibly  the  first  expression  in  England,  outside 
of  scientific  circles,  of  the  general  advantages  of  universal  weights 
and  measures,  and  particularly  those  that  would  accrue  to  com- 
merce by  the  adoption  of  a  uniform  decimal  system.  In  1855 
an  international  statistical  congress  was  held  at  Paris,  and  on 
the  motion  of  James  Yates,  a  member  of  the  Eoyal  Society 
of  London,  it  was  decided  to  form  an  International  Association, 
to  advance  the  adoption  of  a  decimal  system  of  weights  and 
measures  and  moneys.  This  association  made  an  examination  of 
the  different  systems  employed  Throughout  the  earth,  and  decided 
that  the  metric,  system,  on  account  of  its  scientific  character  and 
general  availability  for  international  trade,  was  to  be  preferred, 
and  accordingly  made  a  recommendation  in  its  favor.  The 
sentiment  was  further  echoed  by  members  of  the  International 
Jury  of  the  Paris  Exposition  of  1855,  who  formally  adopted 
resolutions  in  favor  of  the  metric  system,  recommending  it  to 
the  attention  of  their  respective  governments,  and  urging  its 
adoption  on  the  ground  that  it  would  not  only  promote  commerce, 


THE   METRIC   SYSTEM   IN   EUROPE  85 

but  also  peace  and  unity  of  feeling  throughout  the  world,  praising 
especially  its  decimal  basis.1 

A  Committee  of  Weights  and  Measures  and  of  Moneys,  com- 
posed of  delegates  of  various  countries  to  the  Paris  Exposition 
of  1867,  was  formed  at  the  initiative  of  these  delegates,  and  took 
action  in  favor  of  the  decimal  system,  and  urged  the  adoption 
of  uniform  weights  and  measures  throughout  the  world.  While 
this  "committee  enjoyed  no  official  standing,  yet  it  adopted  reso- 
lutions recommending  the  study  of  the  metric  system  in  all  the 
schools,  and  its  recognition  in  all  public  meetings.  Furthermore, 
its  exclusive  use  in  scientific  and  statistical  publications,  for 
postal  purposes,  in  the  customs,  as  well  as  in  public  works, 
and  in  all  other  branches  of  government  administration  was 
recommended.2 

In  the  meanwhile,  the  inconvenience  and  confusion  caused  by 
different  weights  and  measures  throughout  Central  Europe  had 
reached  a  point  where  positive  action  was  necessary.  Under 
more  peaceful  conditions,  commerce  and  industry  were  beginning 
to  nourish,  and  the  lack  of  uniformity  in  weights  and  measures 
was  proving  a  serious  hindrance  to  trade.  In  a  comparatively 
small  territory  there  was  a  considerable  number  of  different 
states  with  different  systems  of  weights  and  measures,  as  well  as 
with  different  tariff  and  customs  regulations,  which  seriously 
interfered  with  the  easy  transaction  of  international  business. 
The  multiplicity  of  these  measures  involved  the  employment  of 
an  inordinately  large  number  of  clerks  and  computers  in  custom 
houses  and  counting  rooms  to  change  from  one  system  to  another 
weights,  measures,  and  moneys,  as  specified  in  invoices,  and  other 
documents.  It  was  doubtless  also  realized  that  to  carry  on 
commerce  there  must  be  an  easy  standard  of  comparison  between 
the  goods  of  the  home  country  and  those  of  other  foreign  coun- 
tries. The  money  alone  was  recognized  as  a  sufficient  cause  of 
trouble,  and  extensive  reforms,  such  as  the  decreeing  of  uniform 
(Metric)  weights  for  metallic  currency  by  the  Vienna  Coin 
Treaty  of  January  24,  1857,  and  a  similar  action  by  the  so-called 
Latin  Union  of  1865,  improved  materially  conditions  in  this 
respect,  and  it  may  be  remarked  that  in  both  instances  the 
currency  was  put  on  a  decimal  basis. 

1  Bigourdan,  Le  Systtme  Mttriqiw,  p.  248.  2  Ibid.  p.  248. 


86       EVOLUTION   OF   WEIGHTS   AND   MEASURES 

With  the  weights  and  measures,  however,  the  first  steps  to- 
ward uniformity  were  taken  when  the  metric  system  was  adopted 
for  customs  purposes,  some  time  before  its  legal  adoption  for 
general  use  in  the  separate  states.  Thus  the  German  Zollverein 
(Customs  Unions)1  adopted  for  use  in  the  customs  a  standard 
metric  pound  (zottpfwruT)  which  was  one-half  of  a  kilogram,  and 
with  it  a  centner  of  50  kilograms.  These  units  of  weight  came 
into  effect  January  1,  1854,  and  the  pjund,  which  was  divided 
into  30  loth,  was  adopted~by^the  German- Austrian  Zollverein,  for 
postal  purposes,  on  the  same  date.  In  1856  the  use  of  the  me  trie 
pound  and  centner  was  further  extended,  and  in  1857  a  coin 
pound  or  munzpfund  (500  grams)  was  employed  for  coinage 
purposes.  The  railways  also  followed  the  example  set  by  the 
customs,  and  throughout  the  countries  constituting  the  Zoll- 
verein all  freight  was  weighed  by  the  metric  pound.  Thus  it 
will  be  seen  that  the  entering  wedge  of  the  metric  system  in 
Europe  outside  of  France  was  in  the  adoption  of  uniform  weights 
for  international  trade,  which'  led  to  a  general  knowledge  of  its 
merits  and  appreciation  of  the  advantages  of  uniformity. 

The  natural  and  immediate  result  was  the  adoption  of  the 
"  zollpf und  "  as  the  unit  of  weight  in  a  number  of  states,  and  with 
this  came  a  general  understanding  of  the  inconvenience  attending 
the  use  of  different  standards  for  measures  of  length,  capacity, 
etc.  In  consequence,  a  commission  of  scientific  men  was 
appointed  from  the  federated  German  states  to  examine  the 
question  thoroughly,  and  formulate  a  national  system  of  weights 
and  measures.  They  reported  in  1861  that  the  metric  system 
already  possessed  the  advantages  sought  after,  and  that  greater 
benefits  would  ensue  from  its  adoption  as  a  whole  than  by 
devising  a  new  system  or  by  endeavoring  to  harmonize  existing 
standards. 

The  method  of  the  change  in  Germany  is  well  worth  careful 
study  from  the  student  of  metrology  and  of  public  affairs,  inas- 
much as  here  were  represented  most  of  the  problems  which 

1  The  Zollverein,  or  union  of  German  states  to  secure  among  themselves  freedom 
of  trade  and  uniformity  of  duties  on  foreign  imports,  was  proposed  by  Prussia  in 
1818.  The  North  and  South  German  Unions,  formed  for  this  purpose,  were 
united  in  1829  by  a  treaty  which  became  effective  in  1834,  and  in  1854  a  strong 
union  of  nearly  all  the  German  states  was  brought  about. 


THE   METRIC   SYSTEM   IN   EUROPE  87 

wouJd  be  encountered  were  the  same  change  to  be  made  in  the 
near  future  either  in  the  United  States  or  in  Great  Britain.  In 
fact,  the  conditions  may  be  said  to  be  practically  the  same,  for 
although  standards  and  processes  based  on  Anglo-Saxon  measures 
have  since  developed  to  such  an  extent  that  a  change  would  be  a 
serious  matter,  yet,  at  the  same  time,  the  use  and  knowledge  of 
the  metric  system  have  also  increased,  so  that  on  this  score  the 
change  would  be  far  less  difficult  now  than  it  was  for  Germany 
in  1870.  Furthermore,  reforms  in  arbitrary  gauges  and  methods 
of  measurement  are  now  required  in  various  lines  of  industry  and 
manufacturing,  which  make  the  present  an  especially  appropriate 
time  for  a  general  change  in  measures.  Consequently,  by  study- 
ing methods  and  conditions  in  Germany  at  the  time  of  this 
change,  it  is  fair  to  say  that  an  accurate  knowledge  of  the  general 
features  of  any  present  problems  of  this  description  will  be  gained, 
and  it  is  also  safe  to  say  that  the  final  advantageous  outcome 
would  be  reproduced  in  either  the  United  States  or  Great  Britain, 
though  the  time  necessary  to  accomplish  such  a  consummation  may 
reasonably  be  a  subject  for  difference  of  opinion  and  argument. 

The  first  legislative  step  in  the  introduction  of  the  metric 
system  into  Germany  was  the  adoption  of  resolutions  to  that 
effect  by  the  Federal  Council  and  the  Parliament  of  the  North 
German  Confederation,  which  were  published  under  the  date  of 
August  17,  1868.1  These  resolutions  provided  that  the  metric 
system  should  be  adopted  in  place  of  the  weights  and  measures 
previously  in  use,  and  that  the  system  should  be  optional,  on 
January  1,  1870,  and  obligatory  on  January  1,  1872.  No  change 
in  the  nature  or  execution  of  this  plan  occurred  when  in  April, 
1871,  the  confederation  was  superseded  by  the  empire.  There 
was  duly  established  the  "  Normal- Aichungs-Kommission,"  which 
was  charged  with  the  work  of  furnishing  detailed  directions  and 
specifications  as  to  the  material,  shape,  and  other  characteristics 
of  the  weights  and  measures,  and  also  with  supplying  the 
•"  marking  "  office  and  its  various  local  branches  with  such  imple- 
ments as  would  enable  it  to  mark  and  stamp  all  weights  and 
measures  which  should  be  presented  to  it.  It  was  also  ordered 

1  W.  Foerster  (former  Chief  of  the  German  Bureau  of  Weights  and  Measures, 
and  President  of  the  International  Committee  of  Weights  and  Measures),  pp.  1.2, 
13,  House  of  Representatives,  Report  No.  2885,  54th  Congress,  2nd  Session,  1897. 


88       EVOLUTION   OF   WEIGHTS   AND   MEASURES 

that  the  confederated  governments  publish  the  calculations  giving 
the  figures  for  the  legal  equivalents  of  the  new  weights  and 
measures  as  compared  with  the  old.1  The  Commission  had  charge 
of  the  introduction  of  the  new  system  throughout  the  confedera- 
tion, supervising  all  measures  to  facilitate  its  speedy  acceptance, 
and  with  definitely  carrying  it  into  effect.  The  various  states  of 
the  confederation  appointed  officials  for  the  actual  marking  and 
stamping  of  the  measures  and  weights,  and  prescribed  regulations 
for  the  administration  of  such  bureaus.  In  the  ten  months 
previous  to  the  date  assigned  for  the  beginning  of  the  optional 
use  of  the  metric  weights  and  measures,  the  Commission  provided 
all  the  marking  offices  with  standards  for  the  verification  of  such 
weights  and  measures  as  should  be  presented  to  them  for  legaliza- 
tion, and  immediately  after  these  needs  had  been  met  the 
manufacturers  were  provided  with  proper  standards,  so  that  they 
could  at  once  commence  the  manufacture  of  weights  and  measures 
for  general  sale  and  use.  Such  weights  and  measures,  adequate 
in  number  and  of  high  accuracy,  were  soon  forthcoming,  and  by 
the  end  of  the  first  half  of  the  year  1870  a  large  part  of  the 
people  of  Germany  became  well  acquainted  with  the  new 
measures,  their  decimal  division  appealing  particularly  to  the 
industrial  and  technical  workers. 

In  1870  occurred  the  war  with  France,  and,  while  it  prejudiced 
many  of  the  people  against  the  new  weights  and  measures,  never- 
theless it  more  closely  united  Germany  and  thus  offset  any 
difficulties  on  this  score.  In  short,  on  the  arrival  of  the 
specified  date,  January  1,  1872,  when  the  use  of  the  old  weights 
and  measures  must  cease  and  the  metric  system  be  the  only 
legal  system,  not  only  were  the  new  weights  and  measures 
supplied  to  all  places  throughout  Germany  where  merchandise 
was  sold,  but  the  various  tradesmen  and  others  concerned  had 
actually  learned  the  use  of  meter  sticks,  liter  measures,  and  the 
series  of  gram  weights.  This  record  is  somewhat  remarkable, 
as  in  Germany  there  was  not  one  system  of  weights  and 
measures,  but,  as  has  been  shown,  a  large  number  of  different 
systems  which  the  new  measures  had  to  supplant.  Germany, 
however,  enjoyed  one  great  advantage  in  the  adoption  of  the 
metric  system  in  the  extensive  use  in  a  number  of  the 
1  Same  Report,  pp.  7,  8. 


THE   METRIC   SYSTEM   IN   EUROPE  89 

states  of  the  "  zollpfund "  or  customs  pound,  above  mentioned, 
which  we  have  seen  was  the  weight  of  500  grams  or  a  half 
kilogram.  Weights  of  this  denomination  were  actually  in 
existence  in  considerable  numbers  and  were  widely  employed, 
but  the  subdivisions  were  not  usually  on  a  decimal  or  metric 
basis,  and  only  in  one  state,  Hanover,  was  there  a  division  into 
1000  half  grams.  Two  of  these  pfund  weights  immediately 
furnished  a  legal  kilogram,  and,  while  their  use  interfered 
somewhat  with  the  development  of  the  decimal  principle,  never- 
theless it  served  to  accustom  the  people  at  large  to  the  new 
mode  of  reckoning.  The  liter  measures  were  accepted  even 
more  readily  than  those  of  mass.  The  relation  between  the 
unit  or  liter  and  the  measure  of  length  and  the  weight  of  water 
served  to  commend  the  new  system  readily  to  those  dealing 
with  fluids,  while  a  number  of  simple  tables  were  prepared 
officially  to  explain  the  simplicity  of  the  system. 

In  contrast  to  the  ease  with  which  the  liter  and  the  gram 
series  were  adopted,  mention  must  be  made  of  the  change 
in  the  measures  of  length.  The  principal  measures  of  length 
were  the  ell  and  the  foot,  which,  though  varying  greatly  among 
the  various  German  states  from  a  metrological  standpoint,  were 
approximately  the  same,  or  sufficiently  so  at  least,  to  convey 
to  the  ordinary  person  a  certain  rough  idea  of  extension  which 
for  many  purposes  sufficed.  Furthermore,  the  foot  and  ell 
differed  so  much  from  the  meter  and  its  subdivisions  that  the 
purchasing  public  could  not  transfer  readily  the  price  of  cloth  or 
other  material  when  conceived  or  expressed  in  these  units  to  the 
meter,  and  thus  obtain  even  an  approximate  idea  of  value.  It 
was  also  argued  that  the  meter  was  not  as  convenient  to  think 
in  as  the  foot  for  architects  and  mechanics,  by  some  of  whom 
opposition  to  the  new  measures  was  manifested ;  but  this  feeling 
soon  died  away,  and  the  new  measures  were  soon  universally 
employed  in  all  works  and  calculations. 

That  the  metric  system  has  contributed  materially  towards  the 
upbuilding  of  German  commerce  and  industry  is  universally 
conceded,  but,  of  course,  since  its  adoption  so  many  causes  have 
acted  to  this  end,  that  it  is  not  possible  to  state  precisely  just 
what  part  the  international  measures  have  played.  Suffice  it  to 
say,  that  in  manufacturing,  especially  of  articles  where  precision 


90       EVOLUTION   OF   WEIGHTS   AND   MEASURES 

of  measurement,  and  interchangeability  of  parts  are  essential, 
the  Germans  have  vastly  improved  and  increased  their  output, 
which  must  in  a  certain  degree  be  due  to  this  cause.  Inasmuch 
as  the  metric  system  was  employed  extensively  in  scientific 
work  previous  to  its  general  adoption,  the  increased  activity .  of 
German  investigators  in  fields  where  measuring  is  essential  is 
not  necessarily  a  result,  but  the  readiness  with  which  industrial 
workers  have  availed  themselves  of  the  scientists'  labors  has 
doubtless  been  facilitated  by  the  fact  that  their  processes  and 
results  were  expressed  in  a  language  that  readily  could  be 
understood.1 

Austria,  where  there  was  much  the  same  variation  of  feet, 
pouno!sr~etc.,  as  in  Germany,  followed  that  country's  example, 
and  on  July  23,  1871,  the  Parliament  passed  a  law  providing 
for  the  permissive  use  of  the  metric  system  after  January  1, 
1873,  and  its  compulsory  use  after  January  1,  1876.  At 
the  same  time  it  published  official  tables  of  equivalents 
between  the  old  and  new  measures,  and  established  a  standard 
meter,  which  was  an  end  standard  of  glass,  and  a  standard 
kilogram  of  rock  crystal,  these  being  legally  supplanted  in 
1893  by  the  copies  of  the  international  standard  meter  and 
kilogram  received  from  the  International  Bureau.  The  old 
measures,  especially  those  known  as  the  "  Lower  Austrian 
System,"  were  quite  unlike  those  of  the  metric  system,  and  at 
first  it  would  appear  that  there  would  have  been  great  difficulty 
in  bringing  about  a  change ;  but  for  a  while  a  binary  system 
of  division  was  tolerated,  and  certain  weights  and  measures 
approximate  in  value  to  the  older  ones  temporarily  were 
employed.  In  the  meantime  newspapers  and  schools  were 
zealously  educating  the  people  to  the  new  order,  while  the 
government  prepared  an  adequate  number  of  approved  weights 
and  measures,  as  well  as  supervised  the  construction  of  others 
according  to  standard  regulations.  The  four  years  appointed 
for  the  transitional  period  proved  ample,  and  there  was  no 
expressed  or  obstinate  resistance  on  the  part  of  the  people. 
In  fact,  it  was  the  general  opinion  that  any  lack  of  completeness 

1See  Promemoria  of  German  Imperial  "  Normal- Aichungs  Kommission  "  in 
House  of  Representatives,  Report  No.  2885,  54th  Congress,  2nd  Session,  1897, 
pp.  7-9. 


THE   METRIC   SYSTEM   IN   EUROPE  91 

in  the  adoption  of  the  system  was  due  rather  to  laxity  on  the 
part  of  the  municipal  authorities  than  to  any  pronounced  feeling 
of  the  public  at  large.1 

In  Hungary,  by  the  law  of  XST^Article  VIII.,  the  metric 
system  was  established  to  be  in  force  from  January  1,  187  6^  but 
its  use  was  sanctioned  six  months  earlier,  and  finally,  in  1901,  the 
international  standards  were  duly  established  by  law.  The 
method  of  making  the  change  was  in  the  main  the  same  as  in 
Austria,  and  the  new  weights  and  measures  were  quickly 
naturalized  and  adopted  by  the  people  generally,  though  in 
isolated  districts  the  old  usage  was  maintained  for  many  years. 

Outside  of  France,  Belgium  is  one  of  the  earliest  countries  to 
use  the  metric  system,  as  it  was  established  there  by  the  law  of 
August  21,  1816,  at  a  time  when  that  country  was  united  with 
Holland.2  The  names  of  the  old  units  were  applied  to  the 
metric  values,  but  instruction  in  the  metric  system  was  given  in 
the  schools,  so  that,  after  the  system  had  been  rendered  com- 
pulsory from  J.82jQ^  by  1836  it  was  possible  to  withdraw  the 
Belgian  names,  and  in  1855  the  exclusive  use  of  the  French 

1  See  pp.  9,  10,  House  of  Representatives,  Report  No.  2885,  54th  Congress, 
2nd   Session,    1897.      In   addition  to  this  report,    which    contains    information 
furnished  by  European  governments  to  ambassadors  and  ministers  of  the  United 
States  on  the  subject  of  the  adoption  of  the  metric  weights  and  measures  by 
the  different  countries,  a  summary  of  foreign  legislation  on  the  Metric  System 
prepared  by  J.  K.  Upton,  chief  clerk  of  the  Treasury  Department,  and  later 
Assistant  Secretary  of  Treasury,  contained  in  Report  No.  14,  House  of  Repre- 
sentatives, Committee   on  Coinage,  Weights  and  Measures,  46th  Congress,  1st 
Session,  1879,  has  been  drawn  upon  for  dates  and  details  given  in  the  following 
pages  concerning  the  adoption  of  the  metric  system  by  the  nations  of  Europe. 
Somewhat  more  recent  are  the  summaries  contained  in  Guillaume,  La  Convention 
du  Metre  (Paris,  1902),  Annexe  iv.   pp.  218-226;    "Re'sume"  de  quelques  Legis- 
lations relatives  aux  Poids  et  Mesures,"  Annexe  aux  Proces-verbaux  des  Seances 
du  Comit^  international  des  Poids  et  Mesures,  Session  de  1901,  2e  Serie,  Tome  1 
(Paris,  1901) ;  Reports  from  Her  Majesty's  Representatives  in  Europe  on  the  Metric 
System,  part  i.,  July,  1900,  English  Parliamentary  Accounts  and  Papers,  1900, 
vol.  xc.  ;  Reports  from  Her  Majesty's  Representatives  Abroad,  part  ii.,  February, 
1901,  English  Parliamentary  Accounts  and  Papers,  1901,  vol.  Ixxx.     The  latter 
are  particularly  full,  and  give  an  interesting  account  of  the  transition  period,  as 
well  as  the  extracts  from  the  laws  in  many  instances.     There  is  also  available  the 
Seizieme  Rapport  aux  gouvemements  signatoires  de  la  Convention  du  Metre  and  the 
Comptes  rendus  de  la  deuxieme  Conference  generate  des  Poids  et  Mesures,  1895. 

2  See  antet  p.  82. 


9'2       EVOLUTION   OF   WEIGHTS   AND   MEASURES 

names  and  measures  was  established  by  law.  The  Belgian 
standards  of  mass  and  length  were  copied  from  those  in  France, 
being  legalized  in  1848,  but  they  were  damaged  in  the  fire  of 
1883  at  the  Palais  du  Nation,  so  that  the  international  prototypes 
which  were  received  in  1894,  and  duly  legalized,  were  most 
acceptable. 

The  use  of  the  metric  system  in  Egypt  is  of  interest,  inasmuch 
as  that  country  is  so  largely  under  British  influences,  both 
commercial  and  political.  The  metric  system  was  established  011 
a  permissive  basis  in  1873,  by  a  decree  of  Khedive  Ismail,  which, 
however,  was  not  enforced,  so  that  in  1886  a  commission  was 
appointed  to  consider  the  adoption  of  the  metric  system,  and 
reported  in  its  favor.  By  1892  its  use  had  extended,  so  that  it 
was  possible  for  the  government  to  adopt  it  for  use  in  all  trans- 
actions between  it  and  private  parties,  except  for  measurement  of 
land  and  the  tonnage  of  ships.  It  has  been  employed  in  the 
public  works  department,  where  large  engineering  projects  have 
been  supervised  and  executed  by  British  engineers,  who  have 
recognized  its  many  advantages,  and  also  in  the  customs,  post 
office,  and  railways.  While  the  old  native  measures  still  remain 
in  daily  use,  yet  the  metric  system  is  being  taught  in  the 
government  schools,  and  as  rapidly  as  is  possible  for  an  oriental 
people,  with  their  traditions  and  conservatism,  it  is  growing  into 
increased  use. 

Greece  is  an  example  of  a  country  where  the  Government 
though  having  adopted  the  metric  system  is  unable  to  secure 
its  use  by  the  masses  of  the  people.  The  metric  system  was 
established  by  a  royal  decree  of  September  28,  1836,  with  Greek 
names  for  the  different  weights  and  measures;  but  its  use  is  largely 
confined  to  the  Government  in  its  various  transactions  involving 
measures  of  distance  and  area,  the  Government  in  common  with 
the  general  public  employing  the  oke  =  1'282  kilograms  as  a  unit 
of  weight,  and  a  measure  of  the  same  name  =  T33  liters  as  a 
unit  of  capacity.  This  is  undoubtedly  due  to  the  fact  that  the 
amount  of  international  commerce  in  Greece  is  comparatively 
limited,  and  that  the  people  at  large  have  but  little  interest 
in  general  commerce  as  such,  while  the  Government  is  indisposed 
to  press  reforms  of  this  character. 

The  conquest  of  Lombardy  and  Venetia  by  Napoleon  in  1803- 


THE   METRIC   SYSTEM   IN   EUROPE  93 

was  the  means  of  inaugurating  the  metric  system  in  Italy,  but 
its  general  use  did  not  follow  except  in  governmental  transactions, 
and  the  bulk  of  the  people  resisted  this  effort  on  the  part  of 
foreign  conquerors.  In  some  of  the  various  kingdoms  and  princi- 
palities it  was  found  convenient  to  adopt  the  metric  weights  and 
measures,1  but  it  required  the  establishment  of  the  Kingdom  of 
Italy  in  1861  to  ensure  complete  uniformity  and  the  thorough 
adoption  of  the  system.  Here,  again,  we  see  that  one  of  the 
consequences,  or  possibly  a  necessary  attribute,  of  the  establish- 
ment of  a  nation  from  a  number  of  separate  states  is  that  there 
should  be  a  single  and  uniform  system  of  weights  and  measures. 
Accordingly,  by  the  law  of  July  28,  1861,  the  metric  system  was 
rendered  obligatory  throughout  the  kingdom  after  January  1,  1863, 
and  this  was  reinforced  by  a  law  passed  in  June  23,  1874;  and 
on  August  23,  1890,  the  international  standards  were  established 
by  a  royal  decree. 

The  Japanese  have  for  some  time  used  metric  weights  in  their 
coinage,  and  in  1891  a  law  was  passed  in  which  the  ancient 
measures  were  reorganized  and  based  on  those  of  the  metric 
system,  which  was  also  duly  recognized.  The  various  national 
units,  which  are  divided  either  decimally2  or  sexagesimally,  are 
defined  in  terms  of  the  metric  units,  so  that  little  difficulty 
would  be  experienced  in  passing  from  one  to  the  other,  and, 
in  fact,  tape  measures  are  frequently  graduated  on  both  sides  with 
the  two  scales,  while  on  a  map  both  scales  are  usually  given. 

We  have  seen  above  3  how  the  metric  system  was  introduced 
into  Holland  when  it  formed  one  country  with  Belgium  in 
1816,  and  it  gradually  enjoyed  wider  use  until  in  1869  the 
French  names  were  adopted  to  designate  the  different  units, 
while  permitting  the  older  and  national  names  to  be  used  for 
ten  years  longer.  The  royal  standards  of  the  Netherlands  were 
constructed  by  a  commission  of  Dutch  scientists,  and  while  they 

1  Metric  System  was  made  compulsory  in  Piedmont  in  1845  ;  introduced  into 
Modena  in  1849,  with  eight  years  for  its  gradual  adoption  ;  adopted  in  part 
-of  Papal  States  in  1859;  in  1861  adopted  in  Sardinia;  in  1863  adopted  in 
Neapolitan  provinces,  in  1869  in  Venice,  and  in  1870  in  Rome. 

2 Japanese  measures  below  a  shaku=  '99421  feet  =  ^  meter  are  decimally 
divided,  rendering  their  comparison  with  metric  measures  in  the  case  of 
•drawings  or  diagrams  very  easy. 

3  See  ante,  pp.  82  and  91. 


94      EVOLUTION   OF   WEIGHTS   AND   MEASURES 

resemble  those  of  the  International  Commission,  were  derived 
directly  from  the  standards  of  the  Archives.  The  Dutch 
standard  meter  is  27  microns  longer  than  the  international 
standard. 

When  a  decree  was  issued  in  Portugal  in  1852  providing  for 
the  introduction  of  the  metric  system,  it  was  provided  that  it 
should  be  in  full  legal  operation  within  a  space  of  ten  years.  It 
was  planned  that  the  introduction  should  be  by  successive  stages, 
beginning  with  the  Government,  and  various  schemes  and  tables 
of  legal  equivalents  were  to  be  prepared  and  distributed.  It  was 
not  possible  to  bring  about  the  change  during  the  specified  time, 
so  that  subsequent  statutes  were  necessary,  and  it  was  not  until 
1872  that  the  metric  system  was  officially  in  universal  use.  The 
introduction  of  the  new  weights  and  measures  was  attended  with 
no  difficulty,  save  the  lack  of  intelligence  of  the  people  of  the 
lower  and  agricultural  classes,  and  among  them  the  force  of 
custom  and  tradition  has  proved  so  strong  that  old  weights  and 
measures  still  remain,  though  they  cannot  be  used  in  any  receipt 
or  legal  document.  The  metric  system  is,  however,  greatly 
appreciated  by  the  commercial  interests,  and  is  slowly  but  surely 
making  progress  among  the  people  at  large.  In  fact,  it  will  be 
seen  that  among  intelligent  people  such  a  change  occasions 
comparatively  small  inconvenience  and  is  quickly  effected;  but 
where  there  is  a  low  general  standard  of  education,  as  in  Portugal, 
the  people  are  conservative  and  unwilling  to  accept  innovations, 
as  they  are  unable  to  appreciate  their  utility. 

Eussia,  no  less  than  other  countries,  early  felt  the  necessity  for 
reforms  in  its  systems  of  weights  and  measures,  and  in  1833  the 
original  Eussian  units  were  defined  in  terms  of  English  feet, — 
the  legal  unit  being  the  sag&ne,  which  was  equal  to  seven  English 
feet.  The  standard  for  this  unit  was  constructed  with  great 
exactness,  and  was  compared  with  the  English  yard,  and  from  it 
the  various  other  measures  were  derived.  Nevertheless  it  was 
found  necessary  to  replace  the  sagbne  by  the  archinne,  which  is 
-J-  sagene  or  '71112  meter.  The  metric  system  is  now  permissive 
under  the  terms  of  the  law  of  June  4-Tfr,  1899,  which  became 
effective  January  1,  1900 ;  yet  it  is  noteworthy  that  its  inter- 
national character  is  recognized  by  defining  the  national  stan- 
dards, the  livre  and  the  archinne,  in  terms  of  the  international 


THE   METRIC   SYSTEM   IN   EUROPE  95 

prototypes.1  The  metric  units  are  largely  employed  in  Eussia,  as 
elsewhere,  for  scientific  work,  and  there  is  said  to  be  a  strong 
feeling  towards  the  complete  adoption  of  the  system,  which  for  a 
number  of  years  has  been  used  by  the  pharmacists  of  the  empire, 
and  since  1896  by  the  medical  departments  of  the  Russian  army 
and  navy.  The  metric  system  is  also  used  in  the  customs  ser- 
vice, with  indications  of  further  extensions.  In  Finland,  where  a 
higher  standard  of  education  prevails,  the  metric  system  has  been 
employed  with  considerable  success  since  1892,  and  no  difficulty 
attending  its  introduction  was  experienced. 

Notwithstanding  the  fact  that  a  large  part  of  the  preparatory 
work  in  determining  the  length  of  the  earth's  quadrant  had  been 
done  in  Spain,  that  country  did  not  adopt  the  metric  system  until 
1849,  though  previously  it  had  been  under  discussion,  and  so  early 
as  1 807  a  number  of  metric  scales  had  been  constructed  at  Madrid. 
The  law  of  1849,  which  provided  that  the  system  should  go  into 
force  in  1853,  and  actually  became  operative  throughout  the  entire 
kingdom  in  1855,  defined  the  meter  in  terms  of  the  dimensions  of 
the  earth,  and  the  other  units  as  deduced  from  the  meter.  These 
definitions  remained  in  force  until  1892,  when  the  receipt  of  the 
copies  of  the  international  prototype  meter  and  kilogram,  prepared 
by  the  Bureau  International,  necessitated  the  restatement  of  the 
law  in  which  these  standards  and  their  relation  to  the  inter- 
national prototypes  of  the  Bureau  were  duly  recognized. 

In  Sweden  a  royal  decree  was  issued  November  22,  1878^  by 
which  the  use  of  the  metric  system  was  made  optional  from  the 
following  January  1 ,  and  after  ten  years  was  to  be  made  compulsory. 
The  usual  official  tables  and  information  in  various  and  convenient 
forms  were  distributed  during  this  transition  period,  but  it  was  not 
until  the  end  of  the  appointed  time  that  the  metric  system  came 
to  be  used  generally.  After  that  its  employment  became  prac- 
tically universal  and  no  difficulties  or  opposition  were  experienced. 

In  Norway  the  metric  system  was  employed  in  the  postal 
service,  by  the  Act  of  May  3,  1871,  and  in  the  same  year  the  gram 
was  adopted  as  the  unit  of  weight  by  the  medical  profession  of 
that  kingdom.  In  1879,  on  July  1,  the  use  of  the  metric  system 
for  all  private  business  became  optional,  but  from  this  date  it  was 

1  See  Frocts-verbaux  du  Comitt  international  des  Poids  et  Mesures,  Session  1897, 
p.  155. 


96       EVOLUTION   OF   WEIGHTS   AND   MEASURES 

to  be  used  exclusively  by  the  Government  in  all  its  transactions, 
such  as  the  collection  of  customs  duties,  public  accounts,  taxes, 
etc.  Then  on  July  1,  1882,  the  use  of  the  metric  system  was 
made  obligatory  in  all  transactions,  both  public  and  private,  and 
no  other  weight,  measure,  or  coinage  other  than  metric  was 
permitted.  It  is  interesting  to  note  that  during  the  three  years 
of  the  transitional  period  the  government  altered  certain  of  the 
older  weights  and  measures,  making  them  conform  to  the 
metric  system.  Thus  all  weights  of  one  pound  and  over  during 
the  first  two  years  were  regulated  and  made  over  free  of  cost,  so 
that  the  old  Norwegian  "  skaal-pund  "  and  the  old  "  bismer-pund  " 
used  with  the  steelyards  were  slightly  increased  so  as  to  weigh 
half-kilograms.  Likewise  the  old  "  korn-tonde,"  or  corn  measure, 
was  adjusted  to  hold  140  liters,  and  a  half  measure  to  hold  70 
liters.  In  the  third  year  of  the  change  period,  however,  a  fee  was 
required  for  these  alterations,  and  after  the  compulsory  use  of  the 
new  weights  and  measures  they  were  absolutely  prohibited. 

In  the  case  of  Norway  we  have  an  approximate  statement1  of 
the  cost  of  the  introduction  of  the  metric  system  as  given  in  a 
statement  of  the  value  of  instruments  sold  in  the  years  1877-84 
by  the  Weights  and  Measures  Office,  but  this  does  not  of  course 
include  the  private  sale  of  metric  weights  and  measures.  In  this 
connection  it  must  be  borne  in  mind  that  the  population  of 
Norway  at  this  time  was  somewhat  less  than  2,000,000.2  The 
statement  is  as  follows : 

Public  expenses — 

Purchase  of  standards,  weights  and  measures 

and  apparatus       -  •-      £2,844 

Plans  and  drawings-  217 

Models  -          -   .  306 

Controlling  apparatus  for  town   and  country 

police  -  -  1,650 

Adaptation  of  old  instruments  to  the  metric 

equivalents  3,111 

£8,128 

1  Reports  from  Her  Majesty's  Representatives  in  Europe  on  the  Metric  System, 
parti.,  July,  1900,  pp.  63,  64;  E. P. P.,  1900,  vol.  xc. 

2  Dec.  31,  1882,  1,913,000. 


THE   METRIC   SYSTEM   IN  EUROPE  97 

Private  expenses — 

Adaptation  of  old  instruments  to  the  metric 

equivalents  -          -     £2,044 

Purchase  of  new  metric  instruments     -          -      35,761 

Total  cost  of  introduction    £45,933 

In  Switzerland  there  was  even  more  than  the  usual  diversity  of 
weights  and  measures  in  the  different  cantons,  but  after  1822  in 
some  of  these  divisions  a  system  based  on  the  metric  measures  and 
having  a  foot  of  30  centimeters  and  a  pound  of  500  grams  was 
established.  By  an  agreement  known  as  the  "  Maass  concordats," 
dated  August  17,  1835,  twelve  cantons  united  in  establishing  this 
system,  and  by  subsequent  additions  to  the  convention  and  by 
legislation  it  became  operative  throughout  the  nation,  being  by  an 
Act  of  Dec.  24,  1851,  the  national  and  compulsory  system  through- 
out the  confederation  after  December  31,  1856.  In  this  system 
the  legal  unit  of  length  was  the  pied  or  foot,  equal  to  30  centi- 
meters, divided  decimally,  and  having  such  multiples  as  the  brache, 
2  feet ;  the  aune,  4  feet ;  the  toise,  6  feet ;  the  perche,  10  feet ; 
and  the  lieue,  16,000  feet.  The  lime  or  pound  equal  to  500  grams 
could  be  divided  either  on  a  binary  or  a  decimal  system,  while 
for  dry  capacity  the  unit  established  was  the  quarteron,  equal 
to  15  liters,  and  for  liquid  capacity  the  pot,  equal  to  one  and 
•a  half  liters.  On  July  3,  1875,  the  Federal  Chamber  passed  a 
law  providing  that  the  complete  metric  system  should  be  used 
after  January  1,  1877,  and  that  the  standards  then  in  course 
of  preparation  by  the  International  Commission  should  be  the 
legal  and  national  standards.  These  international  prototype 
standards  were  received  in  1889,  and  were  duly  substituted  for 
the  older  standards. 

In  Turkey,  metrological,  like  other  reforms,  have  not 
achieved "  the  success  deserved,  largely  on  account  of  the  char- 
acter of  the  people  and 'the  Government.  In  1886  a  law  was 
passed  providing  for  the  establishment  of  the  metric  weights  and 
measures  in  Constantinople,  and  making  their  use  compulsory 
after  five  years,  and  in  189j_  ancient  measures  were  confiscated 
and  destroyed  ;  but  it  has  been  recognized  as  practically  impossible 
to  enforce  the  system,  and  old  and  new  units  and  standards  have 
flourished  side  by  side.  In  fact,  experience  demonstrates  the 

G 


98       EVOLUTION   OF   WEIGHTS   AND   MEASURES 

strength  of  the  proposition  that  weights  and  measures  and  their 
preservation  intact  and  uniform  are  correlatives  of  government^ 
and  where  the  latter  is  weak  or  deficient  in  character,  a  satis- 
factory condition  of  these  necessary  adjuncts  to  commerce  cannot 
be  maintained.  Nevertheless,  in  1900,  it  was  reported1  that  all 
scales  imported  into  the  Ottoman  Empire  must  be  marked  in  the 
metric  system,  and  all  weights  and  measures  marked  according  to 
the  old  systems  were  liable  to  confiscation. 

In  England  the  need  of  an  international  and  decimal  system  of 
weights  and  measures  was  realized  as  early2  as  1783  by  James 
Watt,  who  had  considerable  difficulty  in  reducing  the  weights 
and  measures  used  by  Lavoisier  and  Laplace  in  some  experiment 
to  the  English  weights  and  measures  used  by  Kirwan  in  some 
similar  work.  Writing  to  the  latter  under  date  of  November  14, 
1783,  he  said:3  "It  is  therefore  a  very  desirable  thing  to  have 
these  difficulties  removed,  and  to  get  all  philosophers  to  use 
pounds  divided  in  the  same  manner,  and  I  flatter  myself  that 
may  be  accomplished,  if  you,  Dr.  Priestley,  and  a  few  of  the 
French  experimenters  will  agree  to  it ;  for  the  utility  is  so 
evident  that  every  thinking  person  must  immediately  be  con- 
vinced of  it.  My  proposal  is  briefly  this : 

Let  the  philosophical  pound  consist  of  10  ounces  or  10,000  grains. 
„  „  ounce        „        „   10  drachms  or  1000        „ 

drachm     „        „   100  grains. 

Let  all  elastic  fluids  be  measured  by  the  ounce  measure  of  water, 
by  which  the  valuation  of  different  cubic  inches  will  be  avoided, 
and  the  common  decimal  tables  of  specific  gravities  will  im- 
mediately give  the  weights  of  these  elastic  fluids."  Farther  on 
in  the  letter  he  says,  "  I  have  some  hopes  that  the  foot  may  be 
fixed  by  the  pendulum,  and  a  measure  of  water,  and  a  pound 
derived  from  that;  but  in  the  interim  let  us  at  least  assume  a 
proper  division  which  from  the  nature  of  it  must  be  intelligible, 
as  long  as  decimal  arithmetic  is  used." 

1  Board  of  Trade  Journal  (London,  Feb.  22,  1900),  vol.  xxviii.  p.  449. 

2  In  1620  Edmund  Gunter  had  proposed  a  decimal  measure  for  land  with  a 
surveyor's  chains  of  100  links. 

3  A.  Siemens,  Journal  Institution  of  Elect.  Engineers  of  Great  Britain,  vol.  xxxiL 
pp.  278-9. 


THE   METRIC   SYSTEM   IN   EUROPE  99 

A  few  days  later  (Nov.  23,  1783),  Watt  wrote  to  M.  de  Luc 
calling  attention  to  the  difficulties  of  comparing  the  work  of 
investigators  in  different  countries  on  account  of  the  diversity  in 
weights,  and  also  on  account  of  "  the  absurd  subdivisons  used  by 
all  Europe,"  even  if  the  weights  were  the  same.  He  describes 
the  plan  outlined  above,  and  suggests  dividing  the  Paris  pound 
into  1000  parts.  M.  de  Luc  was  asked  to  communicate  with 
Laplace  on  this  subject,  and  three  years  later  when  Watt  visited 
Paris  he  met  Lavoisier,  Laplace,  Monge,  and  Berthollet,  whom  we 
have  seen  were  deeply  interested  in  the  reform  of  weights  and 
measures.  It  is  fair  to  assume  that  the  subject  was  discussed  by 
Watt  among  them,  and  that  they  listened  to  the  suggestions  and 
ideas  of  the  English  engineer,  and  this  view  is  strengthened  by 
the  provision  inserted  in  the  bill  for  the  reform  of  the  French 
weights  and  measures  that  the  French  Academy  and  the  Royal 
Society  appoint  a  joint  committee  to  discuss  universal  weights, 
and  measures.1 

England,  however,  declined  to  co-operate  with  the  International 
Commission  which  examined  the  work  of  the  French  scientists  on 
which  the  metric  system  was  based,  and  this  attitude,  as  well  as 
a  subsequent  antipathy  to  the  French  system,  was  doubtles  due 
to  the  national  feeling  towards  France.  Mention,  however, 
should  be  made  of  the  fact  that  in  1789  Sir  John  Riggs  Miller 
called  the  attention  of  Parliament  to  reforms  in  weights  and 
measures,  moving  for  the  appointment  of  a  committee  "  to 
investigate  and  report  on  the  best  means  for  adopting  an 
uniformity  of  weights  and  measures."  He,  too,  had  in  mind  the 
length  of  the  second's  pendulum  as  a  basis  of  linear  measure,  and 
his  plan  was  supported  by  the  Rev.  George  Skene  Keith,  who 
further  urged  that  any  new  system  should  be  a  decimal  one. 
The  desirability  of  a  decimal  system  that  should  include  not  only 
weights  and  measures,  but  also  coinage,  began  to  be  felt,  and  in 
1814  Sir  John  Wrottesley  brought  such  a  scheme  to  the  notice  of 
Parliament.  The  result  of  the  agitation  was  that  in  1819  a 
commission  which  included  Dr.  Thomas  Young,  William  H. 
Wollaston,  and  Captain  Henry  Kater  reported  adverse  to  the 
adoption  of  the  decimal  scale,  but  the  cause  continued  to  be 

^ee  M'Leod,  "Notes  on  the  History  of  the  Metrical  Measures  and  Weights," 
Nature  (London,  1904),  No.  1792,  vol.  Ix.  pp.  425-427. 


100     EVOLUTION   OF   WEIGHTS   AND   MEASURES 

argued,  and  at  every  discussion  of  changes  in  weights  and 
measures,  the  metric  system  had  its  advocates  in  increasing 
numbers. 

In  1816  a  resolution  was  passed  in  Parliament  providing  for  a 
comparison  of  the  imperial  standard  yard  with  the  French 
standard  meter,  this  duty  being  assigned  to  the  Eoyal  Society. 
That  body  received  from  Paris  two  platinum  meters  which  had 
been  compared  by  Arago  with  the  French  standard.  One  was  an 
end  standard  which  was  exactly  equal  to  the  meter  at  the 
temperature  of  melting  ice,  while  the  other  was  a  line  standard 
which  at  the  same  temperature  was  short  by  '01759  mm.  These 
meters  were  carefully  compared  by  Captain  Kater  with  the 
Shuckburgh  scale,  and  when  referred  to  the  Parliamentary 
standard  the  true  length  of  the  meter  was  determined  at  39*37079 
British  inches,  a  value  which  was  legalized  by  Parliament  in  its 
Act  of  1864  which  permitted  the  use  of  the  weights  and  measures 
of  the  metric  system. 

Meantime  the  scientists  and  others  had  called  for  reforms  in 
the  British  system  which  would  involve  more  than  merely  the 
construction  of  new  standards.  In  considering  this  subject,  and 
especially  in  its  bearing  on  the  adoption  of  a  decimal  system,  a 
committee  of  the  House  of  Commons,  reporting  in  1862,  stated 
that  "  it  would  involve  almost  as  much  difficulty  to  create  a 
special  decimal  system  of  our  own,  as  simply  to  adopt  the  metric 
decimal  system  in  common  with  other  nations.  And,  if  we  did 
so  create  a  national  system  we  would,  in  all  likelihood,  have  to 
change  it  again  in  a  few  years,  as  the  commerce  and  intercourse 
between  nations  increased,  into  an  international  one."  The 
scientific  men,  and  those  who  had  been  careful  observers  at 
international  expositions  and  conventions,  were  now  making  their 
influence  felt,  and  in  1864  was  passed  the  Act  mentioned  above, 
which  allowed  the  use  of  the  metric  system  of  weights  and 
measures.  Not  satisfied  with  this  step,  the  metric  advocates  in 
1868  proposed  a  bill  making  the  system  compulsory,  but  after  a 
second  reading  it  was  dropped.  In  the  meanwhile  the  Standards 
Commission,  of  which  Sir  G.  B.  Airy,  the  astronomer-royal,  was 
chairman,  carefully  studied  the  subject  of  weights  and  measures 
for  the  kingdom,  and  their  second  report,  dated  April  3,  1869,  is 
devoted  to  the  metric  system 


THE   METRIC   SYSTEM   IN   EUROPE  101 

The  status  of  the  metric  system  was  defined  in  1878  by  the 
Weights  and  Measures  Act,  under  the  terms  of  which  (clause  32) 
the  Board  of  Trade  was  authorized  "  to  verify  metric  weights  and 
measures  which  are  intended  to  be  used  for  the  purposes  of 
science  or  of  manufacture  or  for  any  lawful  purpose,  not  being 
for  the  purpose  of  trade  within  the  meaning  of  this  Act." 

The  legislation  of  August  8,  1878,  still  left  much  to  be  desired, 
and  in  !§§*>,  in  response  to  demands  for  further  action,  a  com- 
mittee was  appointed  from  the  House  of  Commons  to  investigate 
the  matter  anew.  This  committee  heard  numerous  witnesses  and 
carefully  considered  their  testimony,  giving  ample  opportunity  for 
both  sides  of  the  question  to  be  discussed.  In  their  report  they 
recommended : 

"  (a)  That  the  metric  system  of  weights  and  measures  be  at 
once  legalized  for  all  purposes. 

"  (b)  That  after  a  lapse  of  two  years  the  metric  system  be 
rendered  compulsory  by  Act  of  Parliament. 

"  (c)  That  the  metric  system  of  weights  and  measures  be 
taught  in  all  public  elementary  schools  as  a  necessary  and 
integral  part  of  arithmetic,  and  that  decimals  be  introduced  at  an 
earlier  period  of  the  school  curriculum  than  is  the  case  at 
present." 

Parliament  acted  on  that  portion  of  the  report  providing  for 
the  legalization  of  the  metric  weights  and  measures  for  all 
purposes,  passing  a  bill  to  that  end  May  27,  1897,  but  hesitated 
when  it  came  to  making  the  system  compulsory.  On  the 
following  year  in  an  Order  in  Council  dated  May  19,  1898,  after 
an  investigation  by  a  committee  of  the  Royal  Society,  the  various 
units  were  defined  and  their  legal  equivalents  in  the  customary 
weights  and  measures  given.  These  differ  by  minute  amounts 
from  those  of  the  United  States. 

In  1903  it  seemed  to  the  members  of  the  Decimal  Association, 
an  influential  organization  which  had  been  formed  to  further  the 
adoption  of  the  metric  system  and  of  a  decimal  system  of  coinage, 
that  popular  feeling  in  favor  of  radical  reforms  in  the  system  of 
weights  and  measures  was  increasing,  and  that  it  was  an  oppor- 
tune time  to  make  another  attempt.  Accordingly  Lord  Belhaven 
and  Stenton  introduced  such  a  bill,  which  was  supported  on  its 
introduction  by  Lord  Kelvin  and  later  by  Lords  Kosebery, 


102     EVOLUTION   OF   WEIGHTS   AND   MEASURES 

Spencer,  and  Tweedmouth,  and  after  a  third  reading  was  passed 
and  sent  to  the  House  of  Commons,  where,  however,  it  was  never 
brought  up  for  passage. 

/  This  bill  was  endorsed  by  a  large  number  of  town,  city,  and 
county  councils,  and  by  over  fifty  chambers  of  commerce,  includ- 
ing some  of  the  most  important  in  the  kingdom.  Furthermore, 
in  addition  to  petitions  from  forty-two  trades  unions,  representing 
some  300,000  members,  received  while  the  bill  was  in  the  House 
of  Lords,  there  was  a  resolution  unanimously  passed  by  the 
/  Congress  of  Trades  Unions  meeting  at  Leeds  in  September,  1904, 
and  representing  some  5,000,000  workmen,  in  which  it  was 
resolved  to  petition  the  House  of  Commons  in  favor  of  the  bill. 
There  were  also  petitions  from  sixty  Teachers'  Associations, 
Inspectors  of  Weights  and  Measures  in  eighty  districts,  and 
thirty  Eetail  Trades'  Associations,  besides  numerous  Chambers 
of  Agriculture  and  Farmers'  Associations./  Thus  it  will  be  seen 
that  the  bill  was  supported  by  eminently  practical  people  as 
well  as  scientists  and  theorists,  and  it  is  interesting  to  state  that 
in  Great  Britain  retail  tradesmen  and  workmen  have  been  alive 
to  the  many  merits  of  the  metric  system. 

The  bill  of  1904  provided  for  the  establishment  of  the  standard 
kilogram  and  meter  from  the  first  day  of  April,  1909,  as  the 
imperial  standards  of  weight  and  of  measure,  though  for  sufficient 
cause  this  date  could  be  postponed  by  an  Order  in  Council.  It 
also  provided  for  Parliamentary  copies  of  the  substituted  imperial 
standards,  and  that  future  deeds,  contracts,  etc.,  must  be  in  terms 
of  the  metric  system.  The  bill  also  made  due  provision  for 
various  adaptations  made  necessary  by  the  change,  and  prescribed 
the  general  method  in  which  it  should  be  carried  out. 

In  Australia  an  active  demand  was  made  for  the  introduction 
of  the  metric  system,  and  in  1905  it  was  proposed  to  introduce 
into  the  Federation  Parliament  a  bill  with  this  object.  In  the 
same  year  the  neighboring  colony  of  New  Zealand  adopted  the 
metric  system  as  its  legal  system  of  weights  and  measures. 

Great  Britain,  however,  played  an  important  part  in  the  de- 
velopment of  scientific  measures,  namely,  in  working  out  the 
C.G.S.,  or  Centimeter-Gram-Second  system,  as  was  done  by  the 
British  Association  for  the  Advancement  of  Science.  This  system 
was  based,  as  the  name  implies,  on  the  metric  units  of  length 


Y     | 

OF 

THE   METRIC   SYSTEM   IN   EUROPE  103 

and  mass,  and  has  been  of  the  greatest  benefit  to  science,  being 
universally  adopted  by  physicists  and  engineers,  and  will  be 
found  discussed  more  at  length  farther  on  in  this  volume.1 

In  Mexico  the  Metric  System  came  into  effect  on  the  first 
of  January,  1862,  in  accordance  with  the  terms  of  a  law  of 
March  15,  1857,  and  a  second  law  of  March  15,  1861,  which 
provided  for  the  exclusive  use  of  the  Metric  Weights  and 
Measures  for  all  purposes.  While  the  new  system  was  adopted 
by  the  Government,  yet  private  individuals  did  not  take  it 
up,  and  there  was  needed  an  imperial  decree,  issued  in  Nov- 
ember, 1865,  which  declared  the  Metric  System  alone  valid 
throughout  the  country.  For  a  number  of  years  the  old  and 
new  measures  were  used  side  by  side,  and  also,  with  the 
introduction  of  railways  and  of  machinery  for  mining  and  other 
purposes  from  the  United  States,  the  English  foot  and  pound ; 
but  gradually  the  Metric  measures  asserted  their  supremacy,  and 
now  they  are  almost  exclusively  used.  Mexico  became  a  party 
to  the  International  Convention  of  Weights  and  Measures  in 
1890,  and  in  1896  it  formally  adopted  the  international  standards 
for  the  meter  and  kilogram. 

Throughout  South  and  Central  America  the  Metric  System 
is  largely  employed,  and  in  nearly  all  cases  it  is  the  legal 
system  of  the  different  countries.  There  has  been,  however, 
great  difficulty  in  maintaining  this  system  as  the  only  one, 
since  in  numerous  instances  the  people  have  preferred  to  use 
the  older  units  derived  from  Spanish  and  other  sources,  while 
exporters  doing  business  with  Great  Britain  and  the  United 
States  have  made  use  of  the  Anglo-Saxon  units.  This,  of 
course,  is  due  in  great  part  to  the  lack  of  stability  of  the 
South  American  governments,  but  conditions  in  this  respect 
are  improving,  and  the  use  of  the  metric  weights  and  measures 
is  now  practically  universal  throughout  South  America.  It 
was  on  this  account  that  representatives  of  these  countries 
assembled  at  the  International  American  Conference  at  Washing- 
ton in  1890  advocated  the  adoption  by  the  United  States  of 
the  Metric  Weights  and  Measures.  Beyond  the  dates  of 
adoption,  as  given  by  the  accompanying  table,  there  is  but 
little  to  say  as  regards  the  individual  countries 

1  See  Chapter  ix.  p.  205i 


104     EVOLUTION   OF   WEIGHTS   AND   MEASURES 

While  in  the  foregoing  paragraphs  an  attempt  has  been 
made  to  summarize  briefly  when  and  how  the  metric  system 
was  adopted  by  the  more  important  nations  of  the  world,  it  is 
possible  to  obtain  this  information  for  the  remaining  countries 
of  the  world  by  reference  to  the  accompanying  tables,  which 
indicate  the  time  at  which  metric  measures  were  first  adopted, 
when  made  compulsory,  and,  so  far  as  can  be  ascertained  and 
briefly  stated,  the  extent  to  which  they  have  replaced  other 
and  older  measures.  These  tables  speak  for  themselves,  and 
illustrate  most  forcibly  the  spread  of  the  system.  They  are 
based  on  a  somewhat  similar  table  published  as  an  Appendix, 
p.  67,  of  a  Eeport  from  the  Select  Committee  on  the  Weights 
and  Measures  (Metric  System)  Bill  [H.L.],  May  5,  1904,  to  be 
found  among  the  Parliamentary  Papers  of  that  year,  on  the 
Eeports  of  British  Consular  officials  abroad,  to  which  reference 
has  already  been  made  (see  footnote,  p.  91),  and  other  official 
sources  of  information. 


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CHAPTER    IV. 
WEIGHTS  AND  MEASURES   IN  THE   UNITED  STATES. 

IN  the  early  days  of  the  American  colonies  the  weights  and 
measures,  like  the  coinage,  were  based  almost  entirely  on  those 
of  the  mother  country,  and  where  statutes  were  enacted  pro- 
viding for  standards,  these  were  derived  from  the  standards 
of  the  Exchequer  of  England.  Inasmuch  as  that  country  was 
the  chief  source  of  supply  as  well  as  a  market  for  merchandise, 
and  the  commercial  dealings  were  very  largely  with  its 
inhabitants,  such  a  condition  was  most  natural,  and  inasmuch 
as  trade  was  not  particularly  extensive,  such  a  system  of 
weights  and  measures  amply  sufficed.1  During  the  Revolution, 
however,  it  was  realized  that  all  possible  means  should  be  taken 
to  secure  uniformity  in  commercial  practices,  and  the  need  of 
a  single  national  system  of  money  and  weights  and  measures 
was  early  appreciated.  In  the  Articles  of  Confederation  adopted 
by  the  Continental  Congress,  November,  15,  1777,  it  was  pro- 
vided in  section  4,  article  ix.,  that  "  The  United  States  in 
Congress  assembled  shall  also  have  the  sole  and  exclusive 
right  and  power  of  regulating  the  alloy  and  value  of  coin 
struck  by  their  own  authority,  or  by  that  of  the  respective 
states ;  fixing  the  standard  of  weights  and  measures  throughout 
the  United  States ;  .  .  ."  By  the  Federal  Constitution,  Congress 
is  explicitly  given  the  power  to  fix  the  standard  of  weights 
and  measures,  the  fifth  paragraph  of  section  8  of  article  i. 
stating  that  the  Congress  shall  have  the  power  "  to  coin  money, 

1  See  John  Quincy  Adams,  "  Report  on  Weights  and  Measures  "  (Washington, 
1821),  for  summary  of  colonial,  state,  and  territorial  legislation,  pp.  94-117. 


110     EVOLUTION   OF   WEIGHTS   AND   MEASURES 

regulate  the  value  thereof  and  of  foreign  coins,  and  fix  the 
standards  of  weights  and  measures."  It  is  somewhat  curious 
that  the  fixing  of  the  standards  of  weights  and  measures  is 
almost  the  only  power  expressly  and  specifically  conferred  on 
Congress  which  that  body  has  refrained  from  exercising  down 
to  the  present  time,  notwithstanding  its  constant  and  most 
active  interest  in  the  coinage  of  money,  as  evinced  by  a  vast 
amount  of  discussion  and  legislation. 

In  the  days  before  and  during  the  Eevolution  the  coinage  of 
various  nations  as  well  as  from  different  state  mints  passed  in 
circulation,  causing  an  inexpressible  confusion  of  values  and  rates 
of  exchange,  and  it  was  but  natural  that  uniformity  and  sim- 
plicity should  be  desired.  That  this  could  best  be  attained  by  a 
decimal  system  was  appreciated  as  early  as  1782,  when  Eobert 
Morris,  the  Superintendent  of  Finance,  an  office  corresponding  to 
that  of  the  present  Secretary  of  the  Treasury,  wrote  to  the 
President  of  Congress  "  that  it  was  desirable  that  money  should 
be  increased  in  the  decimal  Eatio,  because  by  that  means  all 
calculations  of  Interest,  exchange,  insurance,  and  the  like  are 
rendered  much  more  simple  and  accurate,  and,  of  course,  more 
within  the  power  of  the  great  mass  of  people.  Whenever  such 
things  require  much  labour,  time,  and  reflection,  the  greater 
number  who  do  not  know,  are  made  the  dupes  of  the  lesser 
number  who  do."  1  In  accordance  with  the  suggestions  made,  an 
elaborate  report  on  the  question  of  a  system  of  currency  for  the 
United  States  was  prepared  by  Thomas  Jefferson,  and  on  July  6, 
1785,  a  decimal  system  of  coinage  was  adopted.2  In  the  following 
year,  August  8,  the  complete  system  was  duly  determined,  and 
the  amounts,  nomenclature,  and  value  of  the  various  coins  fixed.a 
The  success  of  the  new  currency  was  soon  assured,  and  it  received 
favorable  commendation  both  at  home  and  abroad. 
/  The  reasons  influencing  its  adoption  would  seem  to  have 
demanded  a  similar  system  of  weights  and  measures,  and  it  is 
perfectly  evident  that  clear  thinkers  like  Morris  and  Jefferson 

1  Watson,  History  of  American   Coinage   (New   York,  1899),  p.   10,    quoting 
from  Wharton's  Diplomatic  Correspondence,  vol.  v.  pp.  103-110. 

2  See  Watson,  p.  16  ;  also  MS.  Reports  of  Committee  on  Finance  of  the  Continental 
Congress,  No.  26,  pp.  537-560. 

3  Journal  of  Congress,  vol.  xxxviii.  No.  1. 


. 


WEIGHTS  AND  MEASURES  IN  UNITED  STATES     111 

were  alive  to  its  advantages?  but  even  at  these  early  times,  as 
well  as  subsequently,  there  was  considerable  disinclination  on 
the  part  of  Congress  to  take  any  measure  looking  toward  the 
establishment  or  reform  of  these  important  adjuncts  to  commerce. 
In  fact,  while  there  have  been  numerous  suggestions  on  the 
subject  of  weights  and  measures  from  Presidents  in  their  messages,, 
there  has  been  comparatively  little  legislation,  and  more  has  been 
accomplished  in  the  way  of  establishing  and  changing  standards 
oy  Executive  order  than  by  direct  legislation. 

President  Washington,  however,  early  realized  the  importance 
of  the  matter,  and  in  his  first  speech  or  message  to  Congress,, 
delivered  January,  8,  1790,  he  said,  "  Uniformity  in  the  currency, 
weights,  and  measures  of  the  United  States  is  a  subject  of  great 
importance,  and  will,  I  am  persuaded,  be  duly  attended  to." 
Accordingly,  the  House  of  Eepresentatives  referred  the  matter  to 
the  consideration  of  the  Secretary  of  State,  Thomas  Jefferson,  and 
requested  him  to  prepare  a  report  dealing  with  the  subject.  Mr. 
Jefferson  had  been  in  Paris  as  Minister  of  the  United  States,  and 
doubtless  was  well  acquainted  with  the  measures  to  reform  the 
weights  and  measures  of  that  country  which  had  been  and  were 
then  under  discussion.  For  this  reason,  as  well  as  on  account  of 
his  connection  with  the  establishment  of  the  national  currency  on 
a  decimal  basis,  his  selection  was  most  fortunate,  and  within  a 
few  months  (July  4,  1790)  a  report  was  submitted  containing  two 
complete  and  distinct  plans.1  He  suggested  as  the  standard  of 
linear  measure  a  uniform  cylindrical  rod  of  iron  of  such  length 
that  in  45  degrees  latitude  at  sea  level  and  constant  temperature 
it  should  perform  its  vibrations  in  small  and  equal  arcs  in  one 
second  of  mean  time.  Such  a  rod  would  have  a  length  of  58*72368 
inches,  corresponding  to  a  length  of  a  seconds'  pendulum  of 
3914912  inches.  In  one  of  the  plans  proposed  he  adapted  the- 
existing  system  to  this  standard,  thus  securing  uniformity  and 
stability,  while  in  the  other,  which  he  considered  available  for 
future  use,  he  proposed  a  new  and  strictly  decimal  system  which 
was  remarkably  complete  and  comprehensive.  Mr.  Jefferson  was 
convinced  of  the  utility  of  the  decimal  system,  and  in  his  proposed 
scheme  of  weights  and  measures  for  the  American  people  he  aimed 

1  See  The  Works  of  Thomas  Jefferson  (edited  by  H.  A.  Washington,  New  York, 
1884),  vol.  vii.  pp.  472-495. 

1° 


112     EVOLUTION   OF   WEIGHTS   AND   MEASURES 

to  reduce  "  every  branch  to  the  same  decimal  ratio  already  estab- 
lished in  their  coins,  and  thus  bringing  the  calculation  of  the 
principal  affairs  of  life  within  the  arithmetic  of  every  man  who 
can  multiply  and  divide  plain  numbers."  The  success  which  has 
attended  the  decimal  currency  of  the  United  States  shows  that 
Jefferson  was  wise  in  his  plan  for  a  similar  division  for  weights 
and  measures,  and  had  his  proposals  been  adopted  much  confusion 
and  inconvenience  would  have  been  spared  the  people  of  the 
United  States.  Furthermore,  but  little  difficulty  would  have 
attended  its  adoption,  as  the  fundamental  unit,  the  foot,  differed 
but  slightly  from  the  foot  then  in  use.  This  foot  was  derived  by 
Jefferson  by  taking  one-fifth  of  the  length  of  the  rod  forming  the 
second's  pendulum  and  then  employing  multiples  and  sub-multiples 
in  building  up  a  series  of  measures  of  length.  A  table  of  these 
units  would  read  as  follows  : l 

10  points  make  1  line. 
10  lines  make  1  inch. 
10  inches  make  1  foot. 
10  feet  make  1  decad. 
10  decads  make  1  rood. 
10  roods  make  1  furlong. 
10  furlongs  make  1  mile. 

Naturally  the  squares  and  the  cubes  of  these  units  formed  the 
units  for  area  and  volume,  while  for  capacity  the  cubic  foot  was 
selected  forming  the  bushel,  which  was  then  divided  and  multi- 
plied decimally  to  give  other  measures.  Likewise  the  cubic  foot 
of  water,  which  weighed  100  pounds  of  10  ounces  each,  gave  the 
basis  of  the  measures  of  weight,  and  these  also  were  arranged 
decimally.  Hardly  too  much  in  praise  of  this  system  of  Jeffer- 
son's can  be  said,  and  its  adoption  by  Congress  would  have 
•exerted  a  wonderful  effect  on  metrology,  not  only  in  the  United 
States  but  also  in  the  world  at  large.  It  will  be  remembered 
that  at  this  very  time  France  was  constructing  its  metric  system, 
while  England,  appreciating  the  confusion  attending  its  complex 
and  unwieldy  system  of  measures,  was  in  good  temper  for  a 
change.  Jefferson's  system,  although  designed  to  have  certain 
points  of  contact  with  the  then  existing  system  so  as  to  make 

1  The  Works  of  Thorns  Jefferson  (New  York,  1884),  vol.  vii.  p.  488. 


WEIGHTS  AND  MEASURES  IN  UNITED  STATES     113 

it  easy  of  adoption,  nevertheless  was  perfectly  uniform  and 
symmetrical,  and  while  possibly  less  scientific  and  precise  than 
the  French  system,  yet  it  possessed  all  the  characteristic  features 
of  convenience,  symmetry,  and  completeness.  Congress  received 
this  able  report,  but  did  not  adopt  either  of  Jefferson's  suggestions, 
doubtless  on  account  of  the  similar  agitation  for  changes  in 
weights  and  measures  then  taking  place  in  France  and  England, 
and  its  desire  to  await  their  outcome. 

The  pressing  need  of  some  action  for  this  country,  neverthe- 
less, was  realized  by  the  executive  branch  of  the  Government, 
and  again  in  his  annual  message  to  Congress  on  October  25,  1791, 
President  Washington  reverted  to  the  subject,  stating  that  "A 
uniformity  in  the  weights  and  measures  of  the  country  is  among 
the  important  measures  submitted  to  you  by  the  Constitution  ; 
and,  if  it  can  be  derived  from  a  standard  at  once  invariable  and 
universal,  must  be  no  less  honorable  to  the  public  councils  thac 
conducive  to  the  public  convenience." 

A  committee  of  the  Senate  appointed  November  1,  1791,  then 
took  the  matter  under  advisement,  and  on  April  5,  1792,  presented 
a  report1  favoring  the  adoption  of  Jefferson's  decimal  plan,  and 
containing  directions  for  the  scientific  construction  of  a  standard 
of  length  which  would  be  divided  into  five  equal  parts,  each  of 
which  would  correspond  to  a  foot.  The  report  also  contained 
information  relative  to  the  measures  for  the  survey  of  land,  units 
of  weights,  etc.  Several  reports  were  submitted  by  this  committee, 
and  it  was  finally  decided  (1793)  "  that  the  Standards  should  be 
the  mean  of  those  found  in  the  country."  No  legislative  action 
was  taken  by  the  Senate,  and  for  several  years  there  is  apparently 
no  record  of  any  great  interest  manifested  in  the  subject  by 
Congress.  In  the  meantime  France  had  adopted  the  Metric 
System  with  a  hope  that  it  would  become  universal,  and  on 
January  8,  1795,  the  President  transmitted  to  Congress  a  com- 
munication2 from  the  Minister  of  the  French  Kepublic,  describing 
in  detail  the  new  system  of  weights  and  measures,  the  standards 
of  length  and  weight,  and  the  method  of  dividing  the  standards 
into  decimal  parts.  A  committee  from  the  House  of  Eepresenta- 
tives  proceeded  to  study  this  plan,  together  with  that  of  Jefferson, 

1  Journal  of  the  Senate,  Second  Congress,  First  Session,  pp.  173,  174. 
2 Executive  Docs.,  Third  Congress,  Second  Session. 

H 


EVOLUTION   OF   WEIGHTS   AND   MEASURES 

and  reported  in  the  following  year ;  but  their  recommendations 
were  of  a  general  character,  and  involved  experimental  work  by 
scientists,  which  was  never  authorized  by  Congress.  It  may  be 
said  in  passing,  Jefferson  did  not  advocate  the  adoption  of  the 
French  system,  as  he  did  not  approve  of  the  use  of  a  fundamental 
unit  derived  from  an  arc  of  meridian  in  preference  to  the  length 
of  a  seconds'  pendulum.1  As  to  his  own  plans,  he  was  not  a 
zealous  advocate  of  either  of  the  propositions  he  had  advanced, 
and  was  willing  to  leave  the  entire  matter  to  Congress. 

The  difficulties  with  France,  the  war  with  Great  Britain,  and 
the  consideration  of  various  matters,  political  and  otherwise,  left 
little  time  for  Congress  to  act  on  matters  of  weights  and  measures, 
and  accordingly  there  was  no  legislative  action  for  a  number  of 
years.  In  the  meantime  the  Coast  and  Geodetic  Survey  requiring 
some  standard  of  length,  imported  from  England,  in  1814,  an 
82-inch  brass  bar  scale  made  by  Troughton  of  London.  Thirty- 
six  inches  taken  on  this  scale,  between  divisions  27  and  63,  were 
adopted  as  the  standard  yard  for  the  United  States  by  the 
Treasury,  and  this  distance  was  used  by  other  departments.2  The 
meter,  however,  was  selected  at  the  outset  for  actual  surveying 
operations  by  the  Coast  and  Geodetic  Survey,  and  for  this  purpose 
has  since  been  continuously  employed  in  its  various  triangulations. 
The  metric  standards  were  a  brass  meter  bar  constructed  in  Paris 
by  Lenoir  in  1813  for  Mr.  Hassler,  and  one  of  the  original 
secondary  iron-bar  standards  constructed  by  the  same  maker  for 
the  French  Metric  Committee  in  1799,  and  presented  to  Mr. 
Hassler  by  Tralles.3  This  latter  standard  was  employed  by  the 
Coast  Survey  until  the  receipt  of  the  international  standards  in 
1890,  and  is  now  to  be  seen  in  the  vault  of  the  Bureau  of 

1  This  is  shown  plainly  in  several  of  Jefferson's  letters  contained  in  the   Works 
of  Thomas  Jefferson  (New  York,    1884),   particularly  those   to    William   Short 
(vol.  iii.  p.  276),  Dr.  Robert  Patterson  (vol.  vi.  p.  11),  and  John  Quincy  Adams 
(vol.  vii.  p.  87). 

2  See  F.  E.  Hassler,  Report  on    Weights  and  Measures,  Document  299,  22nd 
Congress,  1st  Session,  1832,  p.  40.     Also  U.S.  Coast  and  Geodetic  Survey  Report, 
1877  ;  Appendix  12. 

3  See  Hassler,  loc.  cit.,  p.  75,  for  translation  of  Tralles'  description  of  these 
standards.     Also  Transactions  of  American  Philosophical  Soc.  (Phila.,  1825),  vol. 
ii.  p.  252 ;  and  Special  Publication  No.  ^,  U.  S.  Coast  and  Geodetic  Survey,  p.  31 
(Washington,  1900). 


WEIGHTS  AND  MEASURES  IN  UNITED  STATES     115 

Standards   at   Washington.      It   is   of    rectangular   cross   section 
9  mm.  x  29  mm.,  and  is,  of  course,  an  end  standard. 

Keforms  in  weights  and  measures  were  not  proceeding  any  more 
satisfactorily  abroad  than  in  the  United  States.  Great  Britain 
had  been  unable  "  to  reduce  into  any  simple  order  the  chaos  of 
their  weights  and  measures,"1  as  Jefferson  wrote  to  Secretary  of 
State  Adams  in  1817,  while  in  France  the  Metric  System  was  not 
securing  the  ready  adoption  that  was  desired.  The  countries 
conquered  by  Napoleon  and  compelled  to  adopt  it,  returned  to 
their  old  ways  once  compulsion  was  removed;  and  even  in  France, 
as  we  have  seen,  there  was  considerable  doubt  as  to  the  practical 
and  ultimate  success  of  the  new  system,  while  the  decimal  division 
of  time  and  the  decimal  measurement  of  the  circle  had  proved 
distinct  failures.  Therefore,  it  is  not  hard  to  explain  the  hesita- 
tion in  the  United  States  about  adopting  the  French  system. 
That  some  measures  were  needed  we  learn  from  the  message  of 
President  Madison  to  Congress  in  1816,  when  he  said: 

"  Congress  will  call  to  mind  that  no  adequate  provision  has 
yet  been  made  for  the  uniformity  of  weights  and  measures  con- 
templated by  the  Constitution.  The  great  utility  of  a  standard 
fixed  in  its  nature,  and  founded  on  the  easy  rule  of  decimal  pro- 
portions, is  sufficiently  obvious.  It  led  the  Government  at  an 
early  stage  to  preparatory  steps  for  introducing  it,  and  a  com- 
pletion of  the  work  will  be  a  just  title  to  the  public  gratitude." 

Congress  referred  the  matter  to  the  Secretary  of  State,  John 
Quincy  Adams,  and  that  official  undertook  a  thorough  analysis 
and  study  of  the  whole  subject.  To  him  Jefferson  wrote  in  the 
letter  already  quoted  : 2  "  I  sincerely  wish  you  may  be  able  to  rally 
us  to  either  standard,  and  to  give  us  an  unit,  the  aliquot  part 
of  something  invariable  which  may  be  applied  simply  and  con- 
veniently to  our  measures,  weights,  and  coins,  and  most  especially 
that  the  decimal  divisions  may  pervade  the  whole."  Adams 
realized  that  the  matter  was  one  of  extreme  importance  that 
could  not  be  settled  offhand,  and  on  his  own  account  examined 
the  question  in  all  its  many  aspects,  his  conclusions  being  given 
in  a  report3  submitted  on  February  22,  1821,  that  has  since  been 

1  Works  of  Thomas  Jefferson,  vol.  vii.  p.  89. 

Ubid. 

3  J.  Q.  Adams,  Report  upon  Weights  and  Measures,  Washington,  1821. 


116     EVOLUTION   OF  WEIGHTS  AND  MEASURES 

considered  almost  a  classic  in  American  metrology.  While  the 
Secretary  of  State  was  so  engaged,  a  committee  from  the  House 
of  Eepresentatives  also  considered  the  question  of  weights  and 
measures,  and,  January  25,  1819,  submitted  a  report  virtually 
advising  the  adoption  of  the  first  plan  proposed  by  Jefferson,  and 
recommending  that  models  of  the  yard,  bushel,  and  pound,  con- 
forming to  those  in  most  common  use,  be  made  under  the 
direction  of  a  commission  to  be  selected  by  the  President,  and 
which,  if  satisfactory  to  Congress,  should  be  declared  the  standard 
weights  and  measures  of  the  United  States.  Again,  Congress 
failed  to  take  action  on  this  recommendation,  and  when,  two  years 
later,  Secretary  Adams  submitted  his  report,  in  which  he  recom- 
mended that  no  present  change  in  the  weights  and  measures  of 
the  country  be  attempted,  but  that  the  standards  should  remain 
as  they  were,  that  body  had  no  disposition  to  oppose  his  sug- 
gestions, and  nothing  was  accomplished. 

The  report,  however,  is  worth  more  than  passing  notice,  for 
although  Adams  did  not  believe  that  the  introduction  of  the 
Metric  System  into  tKeTTTnited  States  at  that  time  was  prac- 
ticable, nevertheless  he  was  as  alive  to  its  symmetry,  complete- 
ness, and  general  desirability,  as  he  was  to  the  many  advantages 
attending  the  introduction  of  a  universal  system  of  weights  and 
measures  throughout  the  great  countries  of  the  world.  While  it 
is,  of  course,  impossible  to  do  justice  to  the  completeness  and 
philosophic  treatment  of  the  subject  in  this  report  by  any 
summary  or  brief  extracts,  nevertheless  a  few  passages  will  show 
how  keen  was  Mr.  Adams'  understanding  of  the  matter,  and  how 
well  he  appreciated  the  advantages  of  the  French  system.  He 
said : l  "  This  system  approaches  to  the  ideal  perfection  of 
uniformity  applied  to  weights  and  measures,  and  whether  destined 
to  succeed  or  doomed  to  fail,  will  shed  unfading  glory  upon  the 
age  in  which  it  was  conceived,  and  upon  the  nation  by  which  its 
execution  was  attempted,  and  has  in  part  been  achieved.  In  the 
progress  of  its  establishment  there  it  has  often  been  brought  in 
conflict  with  the  laws  of  physical  and  of  moral  nature,  with  the 
impenetrability  of  matter,  and  with  the  habits,  passions,  pre- 
judices, and  necessities  of  man.  It  has  undergone  various 
important  modifications.  It  must  undoubtedly  submit  to  others 

1 J.  Q.  Adams,  Report,  p.  48. 


WEIGHTS  AND  MEASURES  IN  UNITED  STATES     117 

before  it  can  look  for  universal  adoption.  But,  if  man  upon 
earth  be  an  improvable  being ;  if  that  universal  peace,  which  was 
the  object  of  a  Savior's  mission,  which  is  the  desire  of  the 
philosopher,  the  longing  of  the  philanthropist,  the  trembling  hope 
of  the  Christian,  is  a  blessing  to  which  the  futurity  of  mortal 
man  has  a  claim  of  more  than  mortal  promise ;  if  the  spirit  of 
evil  is,  before  the  final  consummation  of  things,  to  be  cast  down 
from  his  dominion  over  men,  and  bound  in  the  chains  of  a 
thousand  years,  the  foretaste  here  of  man's  eternal  felicity,  then 
this  system  of  common  instruments,  to  accomplish  all  the  changes 
of  social  and  friendly  commerce,  will  furnish  the  links  of 
sympathy  between  the  inhabitants  of  the  most  distant  regions ; 
the  meter  will  surround  the  globe  in  use  as  well  as  multiplied 
extention,  and  one  language  of  weights  and  measures  will  be 
spoken  from  the  equator  to  the  poles." 

As  regards  the  metric  or,  as  he  terms  it,  the  French  system  in 
the  abstract  or  as  an  ideal  system,  no  one  could  be  more 
enthusiastic  than  Mr.  Adams.  He  says  : 1  "  The  single  standard, 
proportional  to  the  circumference  of  the  earth;  the  singleness 
of  the  units  for  all  the  various  modes  of  mensuration ;  the 
universal  application  to  them  of  decimal  arithmetic  ;  the  un- 
broken chain  of  connection  between  all  weights,  measures, 
moneys,  and  coins ;  and  the  precise,  significant,  short,  and 
complete  vocabulary  of  their  denominations :  altogether  forming 
a  system  adapted  equally  to  the  use  of  all  mankind ;  afford  such 
a  combination  of  the  principle  of  uniformity  for  all  the  most 
important  operations  of  the  intercourse  of  human  society ;  the 
establishment  of  such  a  system  so  obviously  tends  to  that  great 
result,  the  improvement  of  the  physical,  moral,  and  intellectual 
condition  of  man  upon  earth ;  that  there  can  be  neither  doubt 
nor  hesitancy  in  the  opinion  that  the  ultimate  adoption  and 
universal,  though  modified,  application  of  that  system  is  a  con- 
summation devoutly  to  be  wished." 

The  strongest  praise  for  the  French  system  is  for  the  time 
that  it  will  save,  and  here  Mr.  Adams  states,2  "  Considered 
merely  as  a  labor-saving  machine,  it  is  a  new  power  offered 
to  man  incomparably  greater  than  that  which  he  has  acquired 
by  the  new  agency  which  he  has  given  to  steam.  It  is  in 

1 J.  Q.  Adams,  Report,  p.  90.  zlbid.,  p.  91. 


118     EVOLUTION   OF   WEIGHTS   AND   MEASURES 

design    the   greatest   invention   of    human    ingenuity   since   that 
of  printing." 

Mr.  Adams,  while  he  realized  the  desirability  of  universal 
measures,  believed  that  they  could  only  come  "  by  consent  and 
not  by  force,"  and  mindful  of  the  difficulties  attending  the  intro- 
duction of  the  metric  system  in  France,  and  of  certain  of  its 
features  being  susceptible  of  further  improvement,  thought  it  to 
be  the  best  policy  for  the  United  States  first  to  confer  with 
foreign  nations  as  regards  the  future  and  ultimate  establishment 
of  universal  and  permanent  uniformity,  and,  meanwhile,  to 
secure  for  the  weights  and  measures  in  use  throughout  the 
United  States  a  more  perfect  uniformity  by  suitable  legislation 
especially  avoiding  for  the  time  being  any  innovations.  The 
conclusion  of  the  report  is  no  less  interesting  than  its  other 
sections  :  It  states,1  "  France  first  surveyed  the  subject  of  weights 
and  measures  in  all  its  extent  and  all  its  compass.  France  first 
beheld  it  as  involving  the  interests,  the  comforts,  and  the  morals 
of  all  nations  and  of  all  after  ages.  In  forming  her  system  she 
acted  as  the  representative  of  the  whole  human  race,  present  and 
to  come.  She  has  established  it  by  law  within  her  own  terri- 
tories, and  she  has  offered  it  as  a  benefaction  to  the  acceptance  of 
all  other  nations.  That  it  is  worthy  of  their  acceptance  is 
believed  to  be  beyond  question.  But  opinion  is  the  queenjof_the 
world,  and  the  final  prevalence  of  this  system  beyond  the 
boundaries  of  France's  power  must  await  the  time  when 
the  example  of  its  benefits,  long  and  practically  enjoyed,  shall 
acquire  that  ascendancy  over  the  opinions  of  other  nations 
which  gives  motion  to  the  springs  and  direction  to  the  wheels 
of  power." 

It  is  doubtful  if  a  stronger  statement  of  the  abstract  merits  of 
the  metric  system  could  be  made  than  is  contained  in  this  report. 
Mr.  Adams,  however,  was  injerrorjn  believing  that  concerted 
action  was  necessary  to  secure  the  adoption  of  a  universal  system, 
as  it  has  come  about  gradually,  and  has  been  adopted  by  the 
various  nations  of  the  world  at  such  times  as  seemed  to  them 
suitable  and  convenient.  Again,  experience  has  shown  the  error 
of  Mr.  Adams'  view  on  the  decimal  division  of  the  United  States 
coinage.  He  says  (page  81),  "  The  convenience  of  decimal 

1 J.  Q.  Adams,  Report,  p.  135. 


WEIGHTS  AND  MEASURES  IN  UNITED  STATES     1]9 

arithmetic  is  in  its  nature  merely  a  convenience  of  calculation ; 
it  belongs  essentially  to  the  keeping  of  accounts ;  but  it  is  merely 
an  incident  to  the  transactions  of  trade.  It  is  applied,  therefore, 
with  unquestionable  advantage  to  moneys  of  account,  as  we  have 
done :  yet  even  in  our  application  of  it  to  the  coins,  we  have  not 
only  found  it  inadequate,  but  in  some  respects  inconvenient." 

This  famous  report  has  been  quoted  most  extensively  by 
writers  on  American  metrology,  and  passages  are  cited  with  great 
enthusiasm  by  both  metric  and  anti-metric  advocates  in  support 
of  their  respective  positions.  While  conceding  its  great  breadth 
and  philosophical  character,  yet  at  the  present  time  it  is  worth 
considering  whether  too  much  stress  has  not  been  laid  on  this 
celebrated  document.  Although  President  Adams  was  a  zealous 
student,  errors  of  statement  are  to  be  noted,  while  at  the  same 
time  advances  in  the  science  of  metrology  have  made  it  necessary 
to  look  at  certain  matters  in  a  new  light. 

There  was  at  least  one  department  of  the  U.S.  Government — 
namely,  the  Mint — where  any  uncertainty  of  weight  could  not  for 
obvious  reasons  be  tolerated.  Accordingly,  Minister  Gallatin 
was  instructed  to  procure  from  England  a  copy  of  the  imperial 
standard  Troy  pound  which  had  been  adopted  in  1825.  This  he 
did,  and  the  standard,  after  having  been  most  carefully  compared 
by  Captain  Kater,  was  transmitted  to  the  United  States,  and  by 
Act  of  Congress  of  May  19,  1828,1  was  duly  established  as  the 
coinage  standard  of  the  United  States,  the  Act  being  remarkable 
in  that  it  is  the  only  legislative  Act  legalizing  any  of  the 
customary  measures,  and  establishing  a  standard  for  such  purpose. 
The  Act  provides,  that  "  For  the  purpose  of  securing  a  due  con- 
formity in  weight  of  the  coins  of  the  United  States  to  the 
provisions  of  this  title,  the  brass  troy -pound  weight  procured  by 
the  minister  of  the  United  States  at  London,  in  the  year  eighteen 
hundred  and  twenty-seven,  for  the  use  of  the  Mint,  arid  now  in 
the  custody  of  the  Mint  at  Philadelphia,  shall  be  the  Standard 
troy  pound  of  the  Mint  of  the  United  States,  conformably  to 
which  the  coinage  thereof  shall  be  regulated."  2 

1C.  131,  Sec.  50,  17  statutes  432.     Revised  statutes  3548. 

2  A  description  of  this  standard,  together  with  the  various  certificates  of 
individuals  concerned  with  its  construction,  testing,  receipt,  etc.,  including 
Captain  Henry  Kater,  Minister  Gallatin,  and  President  John  Quincy  Adams, 


120     EVOLUTION   OF   WEIGHTS   AND   MEASURES 

On  May  29,  1830,  the  Senate  passed  a  resolution  ordering  the 
comparison  of  the  standards  of  weights  and  measures  used  by  the 
different  custom-houses,  and  when  these  measures  or  copies  were 
called  in  to  the  Treasury  Department  for  examination,  it  was 
found  that  there  was  the  greatest  lack  of  uniformity  throughout 
the  various  customs  districts.  In  many  cases  the  various  state 
or  local  sealers  of  weights  and  measures  were  appealed  to  not 
only  for  purposes  of  comparison,  but  even  for  the  correction  of 
the  standards.1 

The  resulting  diversity  of  weights  and  measures  naturally  was 
not  without  its  effect  on  the  revenues  of  the  Government,  in 
addition  to  violating  that  section  of  the  Constitution  which  pro- 
vides that  taxes  shall  be  uniform  throughout  the  United  States. 
The  national  standards  upon  which  the  measurements  made  in 
the  custom-houses  were  based  are  thus  described  in  the  following 
extract  from  the  report  of  S.  D.  Ingham,  Secretary  of  the 
Treasury,  March  3,  1831  : 

"  Among  the  instruments  which  had  been  procured,  some  years 
ago,  under  the  direction  of  the  President,  for  the  survey  of  the 
coast,  was  a  standard  measure  of  length,  exactly  corresponding 
with  the  British  Parliamentary  standard,  as  established  in  1758, 
with  which  that  of  1760  is  identical,  as  tested  by  Sir  George 
Shuckburgh  in  1798,  and  by  Captain  Kater  in  1821,  on  the 
occasion  of  the  last  determination  of  the  weights  and  measures  in 
England,  when  it  was  adopted  as  the  legal  unit.  This  standard 
measure  has,  by  means  which  will  be  explained  in  a  future 
report,  been  compared  with  the  pendulum  vibrating  seconds  in 
London,  and  also  with  the  French  meter,  which  is  based  upon 
measurements  of  arcs  of  a  meridian  of  the  earth.  With  such 
evidence  of  its  character,  and  such  an  opportunity  of  correcting 
any  alteration  by  reason  of  decay,  it  was  without  hesitation, 
adopted  as  the  unit  for  the  comparison  of  measures  of  length. 

"  The  troy  pound  used  in  the  Mint  is  known  to  be  identical 
with  the  latest  established  standard  troy  pound  of  Great  Britain, 
as  regulated  by  the  British  laws,  and  standarded  by  Captain 

will  be  found  contained  in  an  interesting  history  of  the  weights  and  measures  of 
the  United  States,  by  0.  H.  Tittman,  in  the  United  States  Coast  and  Geodetic 
Survey  Report  for  1890,  Appendix  18,  pp.  736-8. 

Gassier,  p.  6  (House  of  Reps.  Doc.,  No.  299,  22nd  Congress,  1st  Session). 


WEIGHTS  AND  MEASURES  IN  UNITED  STATES     121 

Kater  in  1824,  having  been  constructed  by  him  at  the  special 
request  of  Mr.  Gallatin,  upon  the  same  principles  and  in  the 
same  manner  that  he  had  employed  in  the  construction  of  the 
British  standard."  l 

Preparations  were  duly  made  to  construct  from  these  standards 
the  standards  for  the  custom-houses,  and  on  June  14, 1836,  a  joint 
resolution  was  adopted  by  both  Houses  of  Congress  providing 
that  there  should  be  constructed  in  the  office  of  the  Coast 
Survey  for  every  state  and  territory,  complete  sets  of  standards 
equal  to  those  made  for  the  custom-houses,  "  to  the  end  that 
a  uniform  standard  of  weights  and  measures  may  be  established 
throughout  the  United  States,"  and  in  July,  1838,  it  was  ordered 
that  balances  for  the  accurate  comparison  of  weights  should  be 
similarly  constructed  and  distributed  to  the  states  and  territories. 
The  standard  weights  were  given  to  the  custom-houses  in  1836, 
and  in  the  following  years  the  standard  yards,  which  were  based 
on  the  Troughton  scale,  and  liquid  measures  were  distributed. 
By  1856  the  various  states  of  the  Union  were  supplied  with 
sets  of  standards,  and  shortly  after  their  receipt  the  individual 
states  enacted  statutes  establishing  them  as  the  standards  of 
weights  and  measures.2  This  work  was  important,  as  being 
the  first  practical  and  systematic  attempt  to  secure  general 
uniformity  of  weights  and  measures  throughout  the  country> 
and  as  an  early  example  of  refined  constructive  scientific  work 
being  carried  on  by  the  national  government  for  the  benefit 
of  the  people  at  large  in  their  commercial  relations. 

It  should  be  said  in  passing  that  the  early  work  of  estab- 
lishing the  standards  of  weights  and  measures  for  the  United 
States  was  done  by  Professor  F.  K.  Hassler,  the  superintendent 
of  the  Coast  Survey,  from  its  inception  to  his  death,  and  during 
these  years  many  interesting  reports  dealing  with  the  scientific 
and  other  features  of  the  work  were  prepared  by  him.3  To 

Extract  from  the  report  of  S.  D.  Ingham,  Secretary  of  State,  March  3,  1831, 
House  of  Representatives,  Doc.  No.  299,  July  2,  1832,  22nd  Congress,  1st 
Session. 

2  See  Laws  Concerning  the  Weights  and  Measures  of  the  United  States,  an  official 
compilation  of   the  United  States  Bureau  of   Standards  of  legislation  on  this 
subject  (Washington,  1904). 

3  See  partial  bibliography  in  House  of  Representatives,  Report  No.  3005,  56th 
Congress,  2nd  Session. 

f  - 


122     EVOLUTION   OF   WEIGHTS   AND   MEASURES 

Professor  Hassler  was  due  the  derivation  of  the  standard  avoir- 
dupois pound  from  the  standard  Troy  pound,  and  so  accurately 
was  the  work  accomplished  that  when  the  British  Government 
sent  over  in  1856  a  copy  of  the  standard  avoirdupois  pound,  there 
was  found  a  difference  of  *001  of  a  grain  between  British  and 
American  standards.  He  also  connected  the  units  of  capacity 
with  those  of  weight,  by  using  in  his  experiments,  which  were 
begun  in  1830,  distilled  water  at  its  temperature  of  maximum 
density,  and  thus  was  able  to  determine  and  construct  accurate 
standards. 

On  the  death  of  Mr.  Hassler  in  1843,  Professor  A.  D.  Bache 
became  the  head  of  the  Coast  Survey,  and  manifested  consider- 
able interest  in  the  work  of  the  Office  of  Weights  and  Measures, 
supervising  the  completion  and  distribution  of  the  state  standards 
begun  by  Mr.  Hassler,  and  in  his  reports  making  recommenda- 
tions looking  towards  the  improvement  of  the  United  States 
system  of  weights  and  measures,  and  also  the  establishment  of 
^universal  system. 

With  the  distribution  of  the  standard  weights  and  measures, 
there  resulted  the  natural  inquiries  as  to  their  origin  and  value, 
and  the  legal  enactments  upon  which  they  were  founded.  Pro- 
fessor Bache  in  his  report  for  18481  summarizes  the  essential 
facts  relating  to  them.  The  actual  standard  of  length  is  the 
82-inch  Troughton  scale  (which  has  been  already  described) ; 
"  the  units  of  capacity  measure  are  the  gallon  for  liquid  and  the 
bushel  for  dry  measure.  j?he  ^a.1|on  is  a  vessel  containing 
58,372'2  grains  (8'3389  pounds  avoirdupois)  of  the  standard  pound 
of  distilled  water,  at  the  temperature  of  maximum  density  of 
water,  the  vessel  being  weighed  in  air  in  which  the  barometer 
is  30  inches  at  62°  Fahrenheit.  The  bushel  is  a  measure 
containing  543,391*89  standard  grains  (7^6214  pounds  avoir- 
dupois) of  distilled  water  at  the  temperature  of  maximum 
density  of  water,  and  barometer  30  inches  at  62°  Fahrenheit." 
The  gallon  is  thus  the  wine  gallon  of  231  cubic  inches  nearly, 
and  the  bushel  the  Winchester  bushel  nearly.  The  temperature 
of  maximum  density  of  water  was  determined  by  Mr.  Hassler 
to  be  39*85°  Fahrenheit.  The  standard  of  weight  is  the  Troy 
pound  copied  by  Captain  Kater  in  1827  from  the  imperial  Troy 
Congress,  1st  Session,  Senate  Executive  Doc.  73  (1848),  p.  8. 


WEIGHTS  AND  MEASURES  IN  UNITED  STATES     123 

pound  for  the  United  States  Mint,  and  preserved  in  that 
establishment.  The  avoirdupois  pound  is  derived  from  this : 
its  weight  being  greater  than  that  of  the  Troy  pound,  in  the 
proportion  of  7000  to  5760 ;  that  is,  the  avoirdupois  pound  is 
equivalent  in  weight  to  7000  grains  Troy.  The  multiples,  as  well 
as  subdivisions  of  the  pound,  are  based  upon  this  standard,  the 
weight  of  which  was  determined  by  the  best  means  attainable  at 
that  time,  in  grain  weights,  by  Troughton,  at  the  Mint,  and  at 
the  Office  of  Weights  and  Measures,  in  presence  of  Mr.  Hassler, 
and  of  the  Director  of  the  Mint,  Dr.  Moore.  From  these 
determinations  resulted  the  pound  weights  of  the  Office  of 
Weights  and  Measures,  which  are  therefore  copies  of  the  Troy 
pound  of  the  United  States  Mint  or  derived  from  it.  The 
pound  is  a  standard  at  30  inches  of  the  barometer  and  62° 
Fahrenheit  thermometer.  The  Troy  pound  of  the  Mint  was 
found,  in  the  comparisons  of  Captain  Kater,  to  be  heavier  than 
the  imperial  Troy  pound  by  only  '0012  of  a  grain. 

"  The  measures  of  length  and  capacity,  and  the  weights  just 
referred  to,  have  been  adopted  by  the  Treasury  Department  as 
standards  for  the  measures  and  weights  of  the  custom  houses  of 
the  United  States,  and  reported  as  such  to  Congress  in  1832.  .  ." 

That  the  system  was  then  unsatisfactory  in  many  respects  we 
have  abundant  testimony.  The  simplification  of  the  existing 
weights  and  measures,  and  the  issuing  of  correct  standards  had 
been  provided  for  as  Adams  had  suggested,  but  nothing  had  been 
done  to  improve  the  system  or  towards  co-operating  with  foreign 
nations  in  establishing  a  universal  system,  as  Adams  had  also 
suggested.  On  the  conditions  as  they  then  existed  Professor 
Bache's  observations  are  of  interest.  In  a  report  made  in  1848 
he  says : x 

"  No  one  who  has  discussed  the  subject  of  weights  and 
measures  in  our  country  has  considered  the  present  arrangement 
as  an  enduring  one.  It  has  grown  up  with  the  growth  of 
European  society,  and  is  deficient  in  simplicity  and  in  system. 
The  labor  which  is  expended  in  mastering  the  complex  denomi- 
nations of  weights  and  measures  is  labor  lost.  Every  purpose 
for  which  weights  and  measures  are  employed  can  be  answered 
by  a  simple  and  connected  arrangement." 

1  Executive  Document  84,  Thirteenth  Congress,  1st  Session,  July  30,  1848. 


124     EVOLUTION   OF   WEIGHTS   AND   MEASURES 

Professor  Bache  believed  that  inasmuch  as  it  was  the  prac- 
tically universal  opinion  of  all  who  had  studied  and  written  on 
American  weights  and  measures  that  the  system  then  in  use 
must  be  considered  temporary,  and  eventually  be  replaced  by  a 
more  convenient  and  systematic  arrangement,  and  wrote  in 
reference  to  Adams'  plan  for  an  international  conference  on  the 
subject  as  follows :  "  The  present  time  seems  especially  to  invite 
an  effort  of  this  kind.  In  England  the  subject  of  weights  and 
measures  is  under  consideration  by  a  commission ;  and  on  the 
Continent  the  new  relations  of  states  hitherto  separated  appears 
to  be  favorable  to  this  object.  Such  changes  can  be  readily 
effected  by  suitable  means  in  one  generation,  by  introducing  the 
new  measures  through  the  elementary  schools."  In  a  subsequent 
report  Professor  Bache  asks,  "  Has  not  the  time  arrived,  in  the 
general  progress  of  commercial  and  international  intercourse,  and 
the  rapid  advance  of  our  own  country  in  science,  wealth,  and 
power,  when  her  voice  should  be  heard  in  an  important  matter 
like  this  ?  Should  not  Congress  make  the  proposition  to  all 
nations,  to  meet,  by  their  representatives,  and  consult  for  the 
purpose  of  establishing  uniformity  of  weights  and  measures  ? 
Such  action  could  not  fail  to  meet  with  a  response  due  to  the 
greatness  of  the  subject,  and  if  the  great  object  be  attained,  to 
lead  to  results  productive  of  vast  and  lasting  benefit  to  the 
human  race." 

While  it  is  quite  natural  that  opinions  in  favor  of  the  adoption 
of  the  metric  system  should  be  given  by  officials  of  the  bureau  of 
weights  and  measures,  and  by  Secretaries  of  the  Treasury,  it  is 
possible  to  recognize  the  beginning  of  a  distinct  general  feeling 
and  movement  in  favor  of  reforms  in  American  weights  and 
measures.  This  may  be  traced  largely  to  the  increasing  numbers 
of  scientific  and  professional  men  who  were  sent  to  Europe  for 
education,  and,  who  having  used  the  metric  system  in  the  schools 
and  laboratories  of  France  and  Germany,  became  enthusiastic 
advocates  of  the  system,  with  the  result  that  on  their  return 
to  the  United  States  they  adopted  it  for  their  own  scientific 
work,  and  taught  it  to  their  students.  In  chemistry  especially 
its  pre-eminence  was  early  recognized,  and  American  chemists 
soon  fell  in  with  the  universal  system  which  by  this  time 
was  employed  in  all  the  European  journals  and  standard 


WEIGHTS  AND  MEASURES  IN  UNITED  STATES     125 

works.1  American  diplomats  and  representatives  to  various  inter- 
national conferences  also  became  convinced  of  the  desirability  of 
a  uniform  system  of  weights  and  measures,  and  their  influence 
was  also  exerted  in  stimulating  a  feeling  in  favor  of  reforms. 

In  February,  1854,  the  American  Geographical  and  Statistical 
Society,  of  which  George  Bancroft,  the  historian  and  Minister  to 
Spain,  was  then  president,  presented  a  memorial  to  Congress  in 
which  the  appointment  of  a  joint  scientific  commission  to  consider 
a  uniform  system  of  weights  and  measures  based  on  a  decimal 
system  was  urged.  This  was  one  of.  the  earliest  of  a  number  of 
similar  resolutions  which  have  since  been  addressed  to  Congress. 
Of  more  importance,  however,  as  corning  from  the  people  at  large 
rather  than  from  scientific  bodies,  were  the  resolutions  adopted 
by  the  legislatures  of  various  States.  The  legislature  of  New 
Hampshire,  by  joint  resolution  approved  on  June  28,  1859,  re- 
quested their  senators  and  representatives  to  urge  upon  Congress 
the  adoption  of  a  decimal  system,  while  the  legislature  of  Maine, 
March  20,  1860,  by  joint  resolution,  expressed  in  still  more 
decided  language,  their  desire  for  a  uniform  international  system 
of  weights,  measures,  and  coins.  This  action  was  soon  followed 
by  a  similar  resolution  by  the  legislature  of  the  State  of  Con- 
necticut, which  in  June,  1864,  took  an  important  step  in  recom- 
mending to  the  proper  school  officers,  that  they  should  provide 
for  the  teaching  of  the  metric  system  in  all  the  schools  of  the 
State.  From  this  time  interest  in  the  metric  system  in  con- 
nection with  the  study  of  the  arithmetic  in  the  schools  increased, 
so  that  the  pupils  within  a  few  years  became  aware  of  the 
existence  of  the  system,  although  often  in  the  method  of  pre- 
sentation of  the  subject  in  text-books,  and  by  teachers  there  was 
little  to  commend  it  to  the  young  mind.  The  problems  were 
usually  those  involving  conversion  from  the  common  system  to 
the  metric,  and  as  such,  were  not  likely  to  inspire  any  great 
degree  of  appreciation  for  the  latter. 

The  Civil  War  so  occupied  the  legislative  and  executive 
departments  of  the  Government  that  there  was  little  opportunity 

1  The  use  of  the  metric  measures  in  American  College  text-books,  in  physics  and 
chemistry,  dates  from  1868-1870.  In  similar  works  for  high  schools  the  new 
system  was  used  from  1878.  R.  P.  Williams  before  Am.  Chem.  Soc.,  June, 
1900. 


126     EVOLUTION   OF   WEIGHTS   AND   MEASURES 

for  any  marked  progress  on  the  part  of  Congress  or  the  officials. 
The  condition  of  affairs  is  stated  by  Salmon  P.  Chase,  Secretary 
of  the  Treasury,  in  his  annual  report  December  9,  1861,  where  he 
writes :  "  The  Secretary  desires  to  avail  himself  of  this  oppor- 
tunity to  invite  the  attention  of  Congress  to  the  importance  of  a 
uniform  system  and  a  uniform  nomenclature  of  weights  and 
measures,  and  coins  to  the  commerce  of  the  world  in  which  the 
United  States  already  so  largely  shares.  The  wisest  of  our 
statesmen  have  regarded  the  attainment  of  this  end  so  desirable 
in  itself  as  by  no  means  impossible.  The  combination  of  the 
decimal  system  with  appropriate  denominations  in  a  scheme  of 
weights,  measures,  and  coins  for  the  international  uses  of  com- 
merce, leaving,  if  need  be,  the  separate  systems  of  nations 
untouched,  is  certainly  not  beyond  the  reach  of  the  daring  genius 
and  patient  endeavor  which  gave  the  steam  engine  and  the 
telegraph  to  the  service  of  mankind.  The  Secretary  respect- 
fully suggests  the  expediency  of  a  small  appropriation  to  be 
used  in  promoting  interchange  of  opinions  between  intelligent 
persons  of  our  own  and  foreign  countries  on  this  subject." 

In  1863  the  United  States  was  represented  abroad  at  two 
important  international  congresses,  both  of  which  took  action  on 
the  matter  of  weights  and  measures  which  commended  itself  to 
the  American  delegates.  At  the  International  Statistical  Con- 
gress held  at  Berlin,  a  committee  appointed  at  the  Paris  meeting 
three  years  previously,  to  consider  the  question  of  uniform 
international  weights,  presented  a  report  in  which  the  subject 
was  carefully  considered  and  as  a  result  of  which  the  Congress 
resolved  that  the  same  measures  for  international  commerce  was 
of  the  highest  importance,  and  that  the  metric  system  was  the 
most  convenient  of  all  that  could  be  recommended  for  inter- 
national measures.1  At  a  previous  session  this  body  had 
recommended  that  the  countries  which  employed  weights  and 
measures  other  than  the  metric  should  give  in  adjoining  columns 
the  metric  equivalents  of  all  statistics. 

The    other    international    congress    referred    to  was  a   postal 

•        I  O  X* 

congress  held  at  Paris  in  May,  1863,  and  which  resulted  in 
important  measures  towards  securing  uniformity  of  weights 

1  Samuel  B.  Ruggles,  Report  on  International  Statistical  Congress  at  Berlin  in. 
respect  to  Uniform  Weights,  Measures,  and  Coins  (Albany,  1864),  pp.  43,  44. 


WEIGHTS  AND  MEASURES  IN  UNITED  STATES     127 

throughout  the  world.  It  was  here  recommended,  that,  "  Sec.  7. 
The  rates  upon  international  correspondence  shall  be  established 
according  to  the  same  scale  of  weight  in  all  countries,"  that 
"  Sec.  8.  The  metrical  system,  being  that  which  best  satisfies  the 
demands  of  the  postal  service,  should  be  adopted  for  international 
postal  relations,  to  the  exclusion  of  every  other  system " ;  and 
that  "  Sec.  9.  The  single  rate  upon  international  letters  shall  be 
applied  to  each  standard  weight  of  15  grams  or  fractional  part  of 
it."  This  proposition  proved  satisfactory  to  the  various  nations 
and  accordingly  was  incorporated  in  the  International  Postal 
Convention. 

In  J866,  when  the  resolutions  authorizing  the  use  of  the 
metric  system  of  weights  and  measures  was  passed  by  the 
Congress  of  the  United  States,  which  is  referred  to  at  more 
length  below,  an  Act  was  also  passed  enabling  the  Post  Office 
Department  to  use  the  metric  weights  and  measures  for  foreign 
and  other  purposes,  and  the  law  was  re-enacted  in  1872  and 
now  reads  (Revised  Statutes  of  the  United  States,  Sec.  3880), 
"  The  Postmaster-General  shall  furnish  the  post-offices  ex- 
changing mails  with  foreign  countries,  and  to  such  other 
offices  as  he  may  deem  expedient,  postal  balances  denoted  in 
grams  of  the  metric  system,  fifteen  grams  of  which  shall  be 
the  equivalent  for  postal  purposes  of  one  half  ounce  avoirdupois, 
and  so  on  in  progression."  The  interchange  of  mail  by  all 
the  civilized  countries  of  the  world  represents  the  most  extensive 
use  of  a  uniform  system  of  weights  and  measures  in  the  world 
and  has  been  carried  on  for  many  years  without  the  slightest 
confusion  or  embarrassment.  All  mail  matter  transported  be- 
tween the  United  States  and  the  fifty  or  more  nations, 
signatories  of  the  International  Postal  Convention,  including 
the  United  States  and  Great  Britain  even,  is  weighed  and  paid 
for  entirely  by  metric  weight. 

The  serious  consideration  of  the  metric  system  in  the  United 
States  by  the  people  at  large  may  be  said  to  date  from  1866 
when  Congress  passed  a  Bill  which  was  approved  by  the 
President  authorizing  the  use  of  the  metric  system  of  weights 
and  measures.  In  this  action  Congress  had  the  advice  of 
the  National  Academy  of  Science,  which  had  appointed  in 
1863,  at  the  request  of  the  Secretary  of  the  Treasury,  a  special 


128     EVOLUTION   OF   WEIGHTS   AND   MEASURES 

committee  to  consider  the  matter.  In  its  report,  which  was 
adopted  by  the  Academy,  occurs  the  following  passage,  which 
seems  to  sum  up  the  situation :  "  The  committee  are  in  favor 
of  adopting,  ultimately,  a  decimal  system:  and  in  their  opinion, 
the  metrical  system  of  weights  and  measures,  though  not 
without  defects,  is,  all  things  considered,  the  best  in  use. 
The  committee  therefore  suggest  that  the  Academy  recommend 
to  Congress  to  authorize  and  encourage  by  law  the  introduction 
and  use  of  the  metrical  system  of  weights  and  measures,  and 
that,  with  a  view  to  familiarize  the  people  with  the  system, 
the  Academy  recommend  that  provision  be  made  by  law  for 
the  immediate  manufacture  and  distribution  to  the  custom- 
houses and  States,  of  metrical  standards  of  weights  and 
measures :  to  introduce  the  system  into  the  post-offices  by 
making  a  single  letter  weigh  15  grammes  instead  of  l^^^j, 
or  half  an  ounce :  and  to  cause  the  new  cent  and  two  cent 
pieces  to  be  so  coined  that  they  shall  weigh  respectively 
5  and  10  grammes,  and  that  their  diameters  shall  be  made 
to  bear  a  determinate  and  simple  ratio  to  the  metrical  unit 
of  length."1  Accordingly,  by  the  law  of  May  16.  1866^  the 
weight  of  the  5  cent  copper  nickel  piece  was  fixed  at  5  grams. 
This  idea  was  extended  to  the  silver  coinage,  and  by  the  law 
of  Feb.  12,  1873  (Revised  Statutes  of  the  United  States,  Sec. 
3513),  it  was  provided  that  "  The  weight  of  the  half  dollar 
shall  be  twelve  grams  and  one-half  of  a  gram ;  the  quarter 
dollar  and  the  dime  shall  be,  respectively,  one-half  and  one- 
fifth  of  the  weight  of  said  half  dollar."  The  4ct_j3assed 
by  Congress  (Revised  Statutes  of  the  United  States,  Sec.  3569) 
on  July281__1866^_  making  the  metric  system  permissive,  pro- 
vided that  "it  shall  be  lawful  throughout  the"~TTnTEed  States 
of  America  to  employ  the  weights  and  measures  of  the  metric 
system,  and  no  contract  or  dealing,  or  pleading  in  any  court, 
shall  be  deemed  invalid  or  liable  to  objection  because  the 
weights  and  measures  expressed  or  referred  to  therein  are 
weights  or  measures  of  the  metric  system."  The  Act  further- 
provided  a  series  of  legal  tables  of  equivalents,  and  upon  them 
are  based  in  the  United  States  all  conversions  from  one  system 

1  House  of  Representatives,    Report   of  the   Committee   on    Coinage,    Weights, 
and  Measures,  46th  Congress,   1st  Session,   Report  No.   14,  p.  23,  part  i. 


WEIGHTS  AND  MEASURES  IN  UNITED  STATES     129 

to  the  other,  as,  for  example,  those  contained  in  the  tables  in 
the  Appendix  of  this  book.  To  further  the  use  of  the  metric 
system  Congress  passed  an  Act,  approved  July  27,  1866, 
authorizing  and  directing  the  Secretary  of  the  Treasury  to 
furnish  to  each  State  one  set  of  the  standard  weights  and 
measures  of  the  metric  system.  With  tMa__jtart  the  metric 
system  has  grown  in  the  United  States,  and  various  measures 
looking  towards  its  final  adoption  have  been  urged  in  Congress 
and  among  the  people  generally. 

The  delegates  to  the  Paris  Exposition  of  1867  were  par- 
ticularly enthusiastic  in  this  respect,  and  among  them  Professor 
F.  A.  P.  Barnard,  President  of  Columbia  College,  who,  with 
.a  number  of  other  advocates  of  reforms  in  weights  and  measures, 
formed  December  30,  1£73,  the  American  Metrological  Society, 
and  was  its  president  until  his  death  ^Tn  18897"  This  society, 
while  interested  in  such  kindred  subjects  as  the  adoption 
of  standard  time  and  international  currency,  carried  on  an 
active  propaganda  in  behalf  of  the  metric  system,  while  the 
Metric  Bureau  which  was  organized  July,  1876,  with  head- 
quarters in  Boston,  supplied  material  both  in  the  way  of 
literature  and  actual  weights  and  measures,  charts,  tables, 
etc.,  that  was  of  the  greatest  assistance  to  the  general  public, 
-especially  teachers,  who  were  now  called  upon  in  many  States 
to  explain  and  teach  the  principles  of  the  system. 

Sufficient  interest  was  manifested  in  the  subject  for  the  United 
States  Government  to  accept  the  invitation  of  the  Government 
of  France  to  send  delegates  to  Paris  to  form  an  international 
commission  to  construct  new  metric  standards.  America  was 
accordingly  represented  by  Professor  Joseph  Henry  and  J.  E. 
Hilgard,  the  latter  being  an  active  member  of  various  important 
committees  concerned  with  the  construction  of  the  standards. 
When  this  commission,  after  reassembling  in  1872,  decided  that 
an  International  Bureau  of  Weights  and  Measures  should  be 
•established  in  Paris,  the  plan  had  the  approval  of  the  delegates 
of  this  country  and  of  the  American  scientific  world  generally, 
the  National  Academy  of  Sciences  formally  favoring  the  scheme 
and  recommending  to  the  Government  the  signing  of  such 
a  treaty.  The  work  of  the  Commission  has  already  been 

lSee  Proceedings,  American  Metrological  Society,  1873-1888  (New  York). 

I 


130     EVOLUTION   OF   WEIGHTS   AND   MEASURES 

discussed,1  and  in  this  connection  it  is  necessary  merely  to  record 
the  fact  that  when  the  American  Minister  to  France,  Mr.  E.  B. 
Washburne,  signed  the  convention,  together  with  delegates  from 
sixteen  other  nations,  agreeing  to  establish  and  support  the 
International  Bureau  of  Weights  and  Measures,  the  United 
States  became  committed  to  the  principle  of  international  weights 
and  measures,  and  privileged  to  participate  in  the  benefits  accru- 
ing from  a  common  system  and  common  standards. 

In  1889,  after  accurate  and  careful  construction  and  adjustment 
and  comparison,  the  international  prototype  standards  of  the 
standard  meter  and  kilogram  were  completed  by  the  bureau,  and 
were  distributed  to  the  various  countries  supporting  the  Com- 
mission. In  a  distribution  by  lot,  the  United  States  received 
meters  Nos.  21  and  27,  and  kilograms  Nos.  4  and  20.  The  seals 
of  meter  No.  27  and  kilogram  No.  20  were  broken  by  President 
Benjamin  Harrison  on-  January  2,  1890,  and  they  were  straight- 
way deposited  in  a  fireproof  room  at  the  Office  of  Weights  and 
Measures  in  the  Coast  Survey  Building.2  These  standards  were 
immediately  adopted  as  the  national  prototype  meter  and  kilo- 
gram, and  the  primary  standards  for  the  United  States,  and  were 
employed  as  fundamental  standards  for  deriving  customary 
units,  the  yard  and  the  pound,  as  well  as  for  constructing  and 
standardizing  secondary  metric  standards.  To  obviate  any 
possible  misunderstanding,  however,  a  formal  order,  approved  by 
the  Secretary  of  the  Treasury,  was  issued  on  April  5,  1893^ 
recognizing  "  the  International  Prototype  Meter  and  Kilogram 
as  fundamental  standards,  and  the  customary  units,  the  yard  and 
the  pound,  will  be  derived  therefrom  in  accordance  with  the  Act 
of  July  28,  1866."3 

Here,  again,  we  find  a  matter  of  fundamental  importance 
settled  by  Executive  order,  and  the  United  States  firmly  com- 
mitted to  the  metric  system  as  the  basis  of  all  measures  in  use, 

1  See  pp.  72-77.  For  text  of  treaty,  diplomatic  correspondence,  reports,  etc  , 
see  chapters  ii.  and  iv.,  Report  No.  14,  46th  Congress,  1st  Session,  House  of  Repre- 
sentatives, Committee  on  Coinage,  Weights,  and  Measures  (Washington,  1879). 

2 For  technical  description  of  the  standards,  certificates,  reports,  etc.,  consult 
Report  U.S.  Coast  and  Geodetic  Survey,  1890,  Appendix  18,  pp.  746-758. 

'Bulletin  No.  26,  U.S.  Coast  and  Geodetic  Survey,  "Fundamental  Standards 
of  Length  and  Mass."  Republished  as  Appendix  No.  6,  1893,  U.S.  Coast  and 
Geodetic  Survey  Report. 


WEIGHTS  AND  MEASURES  IN  UNITED  STATES     131 

no  matter  what  their  source.  So  far  as  fundamental  standards 
go,  the  only  ones  used  by  the  United  Stales~~are  metric  and 
international,  and  to  them  must  be  referred  all  measures,  whatever 
their  nature.  These  standards  are  known  in  their  relation  to 
the  standards  of  the  International  Bureau  at  Sevres,  and  to 
those  of  the  various  foreign  countries,  so  that  in  case  of  their 
destruction  they  could  readily  be  reproduced,  thus  guaranteeing 
the  permanency  of  weights  and  measures  founded  upon  them. 

In  fact,  meter  No.  27  was  transported  to  Paris  in  1904  for 
comparison  with  the  standards  of  the  International  Bureau, 
and  after  several  series  of  careful  observations  its  value  was 
redetermined  in  terms  of  the  international  standard  prototype. 
It  was  found  that  No.  27  at  0°  centigrade  was  too  short  by 
2  microns,  a  discrepancy  greater  by  *55  microns  than  that 
obtained  in  1888,  when  it  was  tested  with  the  other  national 
prototypes.  This  change,  however,  was  so  minute  that  the 
U.S.  Bureau  of  Standards  decided  to  employ  the  old  value 
in  all  of  its  determinations  until  an  opportunity  had  been 
given  to  compare  standard  No.  27  directly  with  the  international 
prototype  meter  and  with  other  national  prototypes.  Inasmuch 
as  the  relation  of  No.  27  to  No.  21  is  accurately  known,  as 
also  are  the  values  of  various  secondary  standards  in  terms 
of  both  national  standards,  it  will  be  seen  that  the  Bureau 
of  Standards  is  now  in  a  position  to  guarantee  the  accuracy 
and  permanency  of  the  measures  of  the  United  States.1 

That  progress  was  being  made  in  the  use  of  the  metric  system 
is  shown  by  the  fact  that    when   Congress,  on  March  3,  1893,      / 
passed  an  Act2  establishing  a  standard  scale  for  the  measurement    * 
of  sheet  and  plate  iron  and  steel,  it  was  expressed  in  terms  of 
both  the  customary  and  metric  measures.     Of  perhaps  greater 
importance    was     the    Act    approved    July    12,    1894    (Revised 
Statutes    of  the    United    States,    Supplement,    vol.    ii.    chap.   131, 
1894),   which    denned    and    established    the    units    of    electrical 
measure.     These  were  the  international  electrical  units  based  on 

^ee  L.  A.  Fischer,  "  Recomparison  of  the  United  States  Prototype  Meter," 
Bulletin  of  the  Bureau  of  Standards  (Washington),  pp.  5-19,  No.  1,  vol.  i. 
1904.  The  discrepancy  mentioned  has  since  been  accounted  for  through  a 
small  error  in  the  coefficient  of  expansion  of  No.  27,  which  was  compared  at 
different  temperatures  in  1888  and  1904. 

2  Revised  Statutes,  3570,  c.  231,  Sec.  1,  27  Statute,  746. 


132     EVOLUTION   OF   WEIGHTS   AND   MEASURES 

the  metric  system  which  were  in  use  by  electrical  engineers 
throughout  the  world,  having  been  definitely  settled  at  a  congress 
held  at  Chicago  in  1893.1 

In  1901  the  National  Bureau  of  Standards  was  established  by 
Act  of  Congress  to  take  over  the  duties  of  the  old  Office  of 
Weights  and  Measures  of  the  Coast  and  Geodetic  Survey,  and 
to  have  somewhat  broader  functions,  especially  in  carrying  on 
standardization  and  other  scientific  work  of  general  public 
advantage.  To  this  bureau  was  assigned  the  custody  of  the 
national  standards  and  the  construction  and  comparison  of 
secondary  and  other  standards  of  weights  and  measures  of  all 
kinds.  In  the  event  of  the  adoption  of  the  metric  system,  it 
would  fall  to  this  bureau  to  oversee  the  construction  and  certify 
to  the  correctness  of  the  many  new  standards  that  would  be 
required  in  science,  commerce,  and  the  arts.  This  it  is  well 
equipped  to  do,  and  has  large  laboratories  with  every  facility  for 
such  work. 

When  new,  territories  were  added  to  the  United  States  as  a 
result  of  the  Spanish  war  in  1898,  it  was  found  that  the  metric 
system  of  weights  and  measures  was  employed  in  both  forto 
Eicp^and  the  Philippine  Islands,  and  the  status  of  the  system  in 
these  possessions  was  duly  confirmed.  In  the  proclamation  of 
the  Military  Governor  of  Porto  Kico,  March  18,  1899,  it  was 
stated,  "  1.  The  use  of  the  metrical  system  of  weights  and 
measures  and  its  nomenclature  are  obligatory.  2.  Its  use  is 
enforced  in  all  transactions,  sales,  contracts,  ...  3.  Wholesale 
and  retail  mercantile  establishments  shall  sell  their  goods  to 
the  public  conformably  to  the  metric  system."  The  Political 
Code  of  Porto  Eico  (1902),  sections  230-246,  definitely  fixes  the 
metric  systems  and  gives  the  legal  definitions.  The  Philippine 
Tariff  Act  (No.  230,  September  17,  1901,  sec.  9)  contained  a  pro- 
vision that  "  The  metrical  system  of  weights  and  measures  as 
authorized  by  sections  3569  and  3570  of  the  Kevised  Statutes  of 
the  United  States,  and  at  present  in  use  in  the  Philippine 
Islands,  shall  be  continued."  In  the  Government  Bill  of  1902  it 
was  provided  that  "  Sections  (of  the  former2  Act)  are  hereby 
amended  by  reducing  all  measurements  therein,  whether  of  dis- 
tance, area,  or  value,  to  the  metric  system." 

1  See  p.  208,  chap.  ix.  2  Philippine  Government  Act  of  1902. 


WEIGHTS  AND  MEASURES  IN  UNITED  STATES     133 

Since  the  first  permissive  legislation  in  J.866,  there  have  been 
various  Bills  introduced  into  Congress  to  establish  the  metric 
system,  and  each  successive  one  has  come  before  Congress  with 
stronger  support,  ~anH' likewise  with  stronger  opposition  on  the 
part  of  those  opposed  to  any  change.  The  matter  of  weights  and 
measures  has  been  investigated  most  carefully  by  various  House 
Committees  on  Coinage,  Weights,  and  Measures,  and  their  reports 
are  replete  with  information  on  the  subject  treated  from  different 
standpoints.  In  1896  two  interesting  reports1  were  prepared 
after  the  committee  had  made  a  careful  consideration  of  the 
subject  extending  over  two  sessions,  and  a  Bill  to  establish  the 
metric  system  was  unanimously  recommended  for  adoption, 
but,  however,  did  not  pass  a  third  reading.  Again  in  1901  a 
somewhat  similar  Bill  was  reported  from  the  Committee,  accom- 
panied by  a  brief  report 2  in  which  its  passage  was  recommended, 
but  unfortunately  this  Bill  was  received  too  late  to  be  considered 
by  the  Congress  then  in  session.  Once  more,  in  1902  and  1903, 
the  subject  was  discussed  in  committee  and  numerous  hearings 
were  held,  the  record  of  which  was  embodied  in  an  interesting 
report3  in  which  the  establishing  of  the  metric  weights  and 
measures  as  the  legal  standards  of  the  United  States  was 
recommended. 

The  general  tendency  of  all  these  Bills  was  the  same.  It  was 
proposed  that  within  a  few  months  after  their  passage,  usually 
at  the  commencement  of  the  next  calendar  year,  that  the  national 
Government  in  all  its  business  relations,  as  well  as  in  all  its 
constructive  work,  should  adopt  the  metric  weights  and  measures 
exclusively,  while  for  the  public  at  large  two  or  three  years 
should  elapse,  after  which  they  would  become  the  legal  system 
of  the  country.  It  was  not  proposed  to  resort  to  compulsory 
measures,  but  to  so  establish  the  new  system  that  it  would 
gradually  extend  into  universal  use.  In  the  Littauer  Bill  intro- 
duced in  1905  it  was  provided  only  that  the  metric  system 
should  be  employed  by  the  Government  in  all  its  transactions 
and  activities. 

1H.R.   Report  No.    795,   and    H.R.    Report  No.    2885,    February    10,    1897, 
54th  Congress. 

2  H.R.  Report  No.  3005,  56th  Congress,  2nd  Session,  March  1,  1901. 
3 H.R.  Report  No.  1701,  57th  Congress,  1st  Session,  April  21,  1902. 


134     EVOLUTION   OF   WEIGHTS   AND   MEASURES 

Secretaries  of  State  and  Treasury,  irrespective  of  political 
party,  as  well  as  other  executive  officers  of  the  Government,  have 
urged  the  adoption  of  the  international  system,  and  diplomats 
and  consuls  have  repeatedly  called  attention  to  the  benefits  to 
commerce  that  would  ensue.  Scientific  men  and  educators  have 
unanimously  urged  the  desirability  of  the  change,  as  have  many 
engaged  in  foreign  commerce.  Against  any  innovation  at  the 
present  time  are  many  manufacturers  and  mechanical  engineers, 
many  of  whom  have  secured  in  their  work  a  considerable  accu- 
racy of  construction,  especially  as  regards  patterns  based  on  the 
English  measures,  which  they  assert  could  only  be  abandoned  at 
an  expense  entirely  incommensurate  with  any  possible  benefit.1 
At  Congressional  hearings,  in  the  scientific  press,  and  at  meetings 
and  conventions,  the  question  has  been  thoroughly  debated  by 
those  interested,  and  the  material  for  information  is  most  ample. 
It  is  now,  however,  a  matter  for  the  American  nation  at  large, 
and  when  the  people  are  thoroughly  convinced  of  the  great 
benefits  that  will  ensue,  there  will  be  no  outcry  against  temporary 
inconvenience.  The  adoption  of  the  metric  system  is  surely  in 
the  line  of  progress,  and  when  once  it  is  realized,  the  United 
States,  with  its  superior  school  system  and  general  high  order  of 
intelligence  possessed  by  its  people,  especially  its  workers,  can 
make  the  change  with  a  minimum  of  embarrassment  and  can 
avail  themselves  of  its  benefits  more  quickly  than  has  been  done 
in  the  past  by  European  nations. 

1  This  point  of  view  will  be  found  strongly  represented  in  Halsey  and  Dale, 
The  Metric  Fallacy,  New  York,  1903,  one  of  the  ablest  of  the  anti-metric  books, 
and  one  that  attracted  considerable  attention  at  the  time  of  its  publication  on 
account  of  the  bitterness  of  its  attacks  on  the  metric  system  and  its  advocates. 
It  furnished  material  for  many  reviews  and  discussions  in  the  technical  press, 
both  favorable  and  hostile.  Of  the  latter  possibly  the  most  interesting  and  able 
were  those  in  the  Electrical  World  and  Engineer  (New  York),  vol.  xliv.  No.  19, 
pp.  784-794,  Nov.  5,  1904,  and  in  The  Physical  Review  (Ithaca),  1904. 

A  somewhat  more  scholarly,  though  less  argumentative  paper  from  a 
similar  point  of  view,  by  George  W.  Colles,  entitled  "The  Metric  versus  the 
Duodecimal  System,"  will  be  found  in  the  Transactions  of  the  American  Society  of 
Mechanical  Engineers,  vol.  xviii.  pp.  492-611,  1896-1897.  See  also  a  paper  by 
J.  H.  Linnard,  "The  Metric  System  in  Shipbuilding,"  Transactions  of  the  Society 
of  Naval  Architects  and  Marine  Engineers  (New  York,  1903),  vol.  ii.  pp.  168-188. 


CHAPTEK  V. 

THE  METRIC  SYSTEM  OF  TO-DAY— ITS  ESSENTIAL  CHAR- 
ACTERISTICS  AND  FUNDAMENTAL  PRINCIPLES. 

THE  metric  system  to-day  represents  a  complete,  uniform,  and 
simple  international  system  of  weights  and  measures,  and  as  such 
may  be  considered  briefly  in  its  entirety,  and  with  a  view  of  the 
relation  of  the  various  units  to  one  another.  In  the  beginning 
it  must  be  understood  that  any  particular  metric  unit  as  such 
does  not  possess  any  intrinsic  superiority  over  other  units,  but 
by  reason  of  being  united  into  a  system  which  is  strictly  Asymme- 
trical and  systematized  on  one  base  ratio  throughout,  and  with 
that  base  ratio^lO,  metric  units  have  many  and  preponderating 
advantages  over  those  of  other  systems.  Nevertheless,  bearing  in 
mind  the  two  conditions  mentioned,  which  are  fundamental,  there 
is  nothing  to  prevent  other  systems  being  constructed  with  other 
units  which  would  no  doubt  be  equally  satisfactory.  But  in  reply 
it  may  be  said,  Why  should  this  be  done,  when  a  system  exists^, 
used  not  only  by  men  of  science  generally  but  by  a  large  part  of 
the  civilized  world,  the  abandonment  of  which  would  surely  accom- 
plish no  particular  purpose.  "  For,"  says  Professor  K.  H.  Smith,1 
"  no  other  can  possibly  be  better  in  practical  essentials  except  in 
substituting  for  ten  the  base  twelve  or  thirty  for  measures  and 
written  numeration  alike,  and  this  latter  is  humanly  impossible." 
For  ordinary  purposes  of  simple  measurement,  units  are 
grouped  into  five  different  classes,  those  pertaining  to  measures  of 

1  Professor  R.  H.  Smith  in  Journal  of  Institution  of  Electrical  Engineers,  quoted 
by  A.  Siemens  in  Proceedings,  Royal  Statistical  Society  (London),  p.  693,  vol.  Ixvi. 
1903. 


136     EVOLUTION   OF   WEIGHTS   AND   MEASURES 

length,  surface,  volume,  capacity,  and  weight,  or,  as  regards  the 
last,  speaking  more  exactly  and  scientifically,  mass.  These  all 
depend  upon  the  meter  as  the  fundamental  unit,  and  as  a  primary 
and  essential  condition  of  the  system,  all  must  bear  a  strictly 
decimal  relation  to  each  other.  Inasmuch  as  in  the  metric 
system  all  are  referred  to  one  primary  standard,  the  Meter,  there 
must  be  necessarily  absolute  uniformity,  and  as  means  have  been 
taken  to  preserve  this  standard  from  any  deterioration  due  to- 
time  or  other  causes,  there  is  every  guarantee  of  the  stability  of 
the  system  and  of  its  standards.  Furthermore,  what  was  once 
deemed  desirable  but  found  to  be  impossible  of  realization,, 
namely,  the  definition  of  a  standard  by  some  object  or  circum- 
stance in  nature,  has  been  accomplished,  and  to-day  we  have  the 
meter  precisely  defined  in  terms  of  the  wave-length  of  cadmium 
light  by  a  method  which  is  described  elsewhere.1  Thus  in  the 
event  of  the  loss  or  the  destruction  of  the  International  Prototype 
Meter  or  of  the  copies  thereof,  it  would  be  possible  to  reproduce 
the  exact  length  by  experiments  that  to  the  practised  physicist- 
involve  no  serious  difficulty. 

With  the  fundamental  unit,  the  International  Prototype  Meter,, 
defined  as  the  distance  between  two  fine  lines  on  a  particular 
platinum-iridium  bar,  at  the  temperature  of  melting  ice,  and 
reproduced  by  national  standards  accurately  copied  therefrom  and 
duly  recognized  by  the  laws  of  the  countries  owning  them,  by 
simply  multiplying  by  ten  successively  or  by  a  similar  simple 
process  of  decimal  subdivision,  is  built  up  a  system  of  measures 
of  length  which  have  been  dem^fcrated  as  sufficient  for  the 
needs  of  science,  commerce,  and  industry.  Each  unit  is 
either  ten,  one  hundred,  one  thousand,  ten  thousand,  or  a  million 
times  as  great  as  the  fundamental  unit  of  length,  the  meter,  or  a 
similar  fraction  or  sub-fraction.  This  relation  for  many  purposes 
it  is  convenient  to  express  by  means  of  the  number  10  and  the 
appropriate  exponent  or  index,  and  then  speak  of  a  certain 
number  of  meters  multiplied  by  10,  102,  103,  104,  106,  or  for  the 
sub-multiples  10-1,  10~2,  10" 3,  etc.  Consequently,  in  a  number 
expressing  a  length  in  a  metric  unit,  it  is  possible  to  change  the 
unit  merely  by  moving  the  decimal  point  or  adding  a  requisite 
number  of  zeros  to  correspond  with  the  necessary  decimal  multi- 
1  See  chapter  x.  pp.  261-266. 


THE   METRIC   SYSTEM   OF  TO-DAY  137 

plication  or  division.  Thus,  as  will  be  seen  from  the  following 
table,  1  kilometer  may  be  written  as  1000  meters  simply  by  adding 
three  zeros  to  the  1,  while  1  decimeter  may  be  expressed  in 
terms  of  the  meter  simply  by  moving  the  decimal  point  one 
place  to  the  left.  Taking  fundamental  units  other  than  those  of 
length,  which,  however,  are  derived  from  the  meter,  a  similar 
method  of  decimal  multiplication  and  subdivision  enables  us  to 
derive  complete  sets  of  units  for  surface,  volume,  capacity,  and 
mass  measurements.  For  the  first  two  we  use  the  square  meter 
and  the  cubic  meter  as  the  fundamental  units,  and  for  capacity 
the  liter,  and  for  mass  the  gram. 

For  the  multiples  of  its  principal  units    the   metric  system 
employs  prefixes  derived  from  the  Greek  as  follows  : 

Deca  meaning  10  times  derived  from  Greek  Sexa  =  10 
Hecto       „        100          „  „  e/caroWlOO 

Kilo         „        1000         „  „  x^"*  =  100° 

Myria       „        10000       „  „  imvpia  =  10000 


Similarly,  prefixes  derived  from  the  Latin  are  employed  for  the 
submultiples  of  the  various  units.     These  are  as  follows  : 

Deci  meaning    ^Q     derived  from  Latin  decem  =  10 
Centi       „         y^Q-         „  „         centum  =  100 

Milli  „  „  mille  =  1000 


These  seven  prefixes  always  used  in  the  same  relation  supply  the 
means  of  obtaining  units  of  a  size  convenient  for  the  work  in 
hand,  and  alway  instantly  available  for  conversion  into  units  of 
another  denomination.  To  facilitate  remembering  the  fact  that 
the  Greek  prefixes  indicate  multiples,  and  the  Latin  the  sub- 
multiples,  one  has  merely  to  think  of  the  word  "  Gild,"  and 
understand  that  it  stands  for  the  initials  of  the  motto,  "  Greek 
increases,  Latin  decreases."  With  the  three  primary  units,  in- 
volving the  three  names  meter,  liter,  and  gram,  and  the  two 
more  arbitrary  units  are  and  stere,  together  with  the  seven 
prefixes  given  above,  it  is  possible  to  construct  all  the  metric 
units  in  ordinary  use,  inasmuch  as  their  relation  to  each  other 
is  perfectly  uniform  and  simple. 


138     EVOLUTION   OF   WEIGHTS   AND   MEASURES 


Metric  Measures  of  Length. 


Unit. 

Abbrevia- 
tion. 

Where  Employed. 

Value  in  Terms 
of  Meter. 

Power 
of  10. 

Megameter,  - 

Astronomy 

1,000,000m. 

lO^m. 

Myriameter, 

Mm. 

Geography 

10,000m. 

104m. 

Kilometer,   - 

Km. 

Distance 

1,000m. 

I03m. 

Hectometer, 

Hm. 

Artillery 

100m. 

102m. 

Decameter,  - 

Dm. 

Surveying 

10m. 

10m. 

Meter, 

m. 

1m. 

Decimeter,   - 

dm. 

Commerce 

•1m. 

10-!m. 

Centimeter,  - 

cm. 

Industry 

•Olm. 

10-2m. 

Millimeter,  - 

mm. 

Science 

•001m. 

10-3m. 

Micron  =  ju,  - 

Metrology 

•000,001m. 

10-6m. 

Millimicron, 

Spectroscopy 

•000,000,001m. 

10-'m. 

Microscopy 

While  the  foregoing  represent  the  various  units  of  length  in 
the  metric  system,  and  indicate  the  principal  departments  of 
knowledge  in  which  they  are  used,  it  does  not  follow  that  all  of 
them  are  used,  or  that  a  given  length  is  expressed  in  terms 
of  more  than  one.  For  example,  a  distance  is  not  expressed  as 
34  kilometers,  9  hectometers,  3  decameters,  and  4  meters,  but 
as  34-934  kilometers,  and  all  measures  of  length,  where  it  is 
desirable  to  use  kilometers,  are  expressed  in  that  unit  and  a 
decimal  fraction.  Thus,  for  each  class  of  measurements,  as  a 
general  rule,  there  is  used  but  one  of  the  above  units,  as  will  be 
discussed  below,  and  any  measurement  is  expressed  in  whole 
numbers  and  decimal  fractions.  Each  of  the  above  units  is  well 
suited  for  a  number  of  varieties  of  measurements,  and  a  few  of 
these  may  be  conveniently  outlined.  The  megameter,  which  has 
not  received  legal  sanction,  is  but  rarely  encountered,  and  then  only 
in  astronomical  work  where  distances  of  considerable  magnitude 
are  discussed.  As  it  appears  only  in  calculations  it  does  not 
possess  much  general  interest,  and  the  same  holds  true  for  the 
myriameter  formerly  used  in  geographical  work.  The  kilometer, 
on  the  contrary,  as  a  unit  of  distance  such  as  would  be  used  in 
the  measurement  of  the  length  of  a  railway  or  road,  is  of  vast 


THE   METRIC   SYSTEM   OF  TO-DAY  139 

importance,  and  is  universally  employed  both  scientifically,  as  by 
engineers,  and  also  in  non-technical  matters.  It  is  a  unit  whose 
use  presents  very  little  difficulty  to  those  accustomed  to  Anglo- 
Saxon  measures,  in  that  it  corresponds  so  closely  to  six-tenths  of 
a  mile  that  such  an  approximation  suffices  for  most  purposes  and 
is  readily  made. 

The  hectometer  does  not  find  extensive  practical  application, 
and  is  encountered  chiefly  in  the  calculations  of  artillerists ;  but 
even  here  it  is  preferable  to  use  meters,  and  velocities,  etc.,  are 
now  usually  calculated  in  the  latter  units.  The  decameter  is 
used  in  surveying  where  it  forms  a  base  for  the  measure  of  land, 
since  the  decameter  squared  gives  the  are,  which  is  the  principal 
unit  of  land  measure.  The  classes  of  measurement  for  which  the 
meter  is  available  are  numerous  and  apparent.  For  the  measure 
of  cloth  and  similar  fabrics  it  is  eminently  suitable,  and  as  the 
yard  is  approximately  *9  of  the  meter  there  is  no  very  violent 
break  in  passing  from  one  to  the  other,  as  would  be  done  by 
the  purchaser  of  cloth  for  a  dress.  The  meter  would  be  used  by 
the  stone  mason  in  the  measurements  of  a  length  of  wall,  or  by  a 
carpenter  or  architect  in  his  specifications  and  plans  for  structural 
work,  and  is  in  every  way  as  suitable  a  unit  as  the  yard,  aside 
from  the  inherent  merits  of  its  connection  with  the  metric 
system.  In  the  decimeter  there  is  a  unit  intermediate  between 
the  meter  and  the  centimeter,  and  on  that  account  not  as  much 
used  as  either.  Furthermore,  the  decimeter  does  not  correspond 
to  any  unit  that  has  been  in  recent  use  by  non-metric  countries, 
and  in  the  Anglo-Saxon  system  its  nearest  equivalent  is  the  hand 
of  four  inches,  long  obsolete,  except  in  measuring  the  height  of 
horses.  The  decimeter  is  too  short  to  fill  the  place  of  the  foot 
and  too  long  to  supplant  such  a  unit  as  the  inch.  Nevertheless, 
it  is  at  the  disposal  of  those  who  desire  such  a  unit,  and  as 
three  decimeters  will  approximate  a  foot,  it  may  find  increased 
application,  but  its  use  has  never  been  great  in  the  countries 
employing  the  metric  system.  The  centimeter,  on  the  other  hand, 
is  a  most  useful  and  convenient  unit,  and  is  susceptible  of  wide 
application.  For  the  carpenter  or  cabinetmaker  in  giving  the 
dimensions  of  a  door  or  window,  the  size  of  a  plank,  that  is,  its 
breadth  and  thickness,  or  the  dimensions  of  any  ordinary  objects, 
.such  as  tables,  chairs,  etc.,  the  centimeter  fills  every  requirement, 


140    EVOLUTION   OF   WEIGHTS   AND   MEASURES 

and  in  scientific  work  it  is  customary  to  express  dimensions  of 
apparatus  and  all  ordinary  measurements  in  its  terms.  For 
many  years  in  the  United  States  library  catalogue  cards  and 
other  furnishings,  such  as  pamphlet  cases,  have  been  standardized 
and  sold  according  to  metric  measure,  and  the  centimeter  ha& 
been  the  unit  adopted.  It  takes  the  "place  of  the  inch,  and  while 
it  requires  a  larger  number  to  express  a  given  distance,  yet  it  is 
likely  to  lead  to  greater  exactness  where  it  is  not  desirable  ta 
employ  fractions.  The  millimeter  is  the  unit  of  science  and 
exact  mechanical  work.  It  affords  an  integral  unit  for  minute 
measures,  speaking  comparatively,  and  its  decimal  subdivision  is 
peculiarly  suitable  for  this  class  of  work.  In  ordinary  life  its 
chief  application  is  to  the  measurement  of  thickness,  such  as- 
metals,  paper,  glass,  etc.,  and  particularly  in  the  measurement 
of  diameters  of  wire,  tubing,  and  other  materials  which  enter 
into  mechanical  construction.  Thus,  measurements  in  millimeters 
are  designed  to  take  the  place  of  arbitrary  gauges  where  the 
problem  of  original  standards,  which  in  turn  are  based  on 
standards  of  length,  works  against  general  uniformity  and  con- 
venience. For  the  measurement  of  screw-threads  the  millimeter 
is  also  employed,  and  in  France,  Germany,  and  Switzerland 
millimeter  sizes  for  screws  and  thickness  and  diameters  have 
been  found  to  be  far  more  convenient  than  arbitrary  gauges, 
While  the  millimeter  answers  many  purposes  of  the  scientist, 
yet  it  does  not  carry  him  far  enough,  and  accordingly  there  is 
the  micron,  which  is  one-thousandth  part  of  it.  This  affords  a 
convenient  unit  for  the  microscopist  and  the  spectroscopist  when 
they  venture  into  the  regions  beyond  the  range  of  the  human 
eye ;  and  to  secure  a  still  greater  refinement  we  have  the 
millimicron,  or  again  the  thousandth  part. 

With  such  units  as  the  foregoing,  the  next  point  is  how  are 
they  applied,  and  how  are  they  concretely  represented  by  scales 
or  other  devices  ?  The  longest  scale  is  that  of  the  geodesist 
or  engineer  employed  in  measuring  his  base  line  for  trigono- 
metrical surveying  of  greater  or  less  accuracy  as  the  occasion, 
may  warrant.  The  best  modern  practice  involves  the  use  of  a 
steel  tape  or  wire,  or  one  made  of  an  alloy  of  steel  with  a  smaller 
tendency  to  expand  and  contract  with  changes  in  temperature, 
which  under  a  constant  tension  gives  an  exact  representation  of 


THE   METRIC   SYSTEM   OF  TO-DAY  141 

a  distance  as  determined  with  a  standard  of  length.1  Such  tapes 
or  wires  are  usually  of  100,  200,  or  300  meters,  while  the  ordinary 
chain  or  tape  of  the  land  surveyor  is  either  a  double  or  single 
decameter  on  which  are  marked  the  meters  and  such  other 
subdivisions  as  are  desired,  the  double  decameter  being  known  as 
a  metric  chain.  The  next  measure  of  length  in  point  of  size 
is  the  double  meter,  which  may  be  either  a  rod  or  tape.  If  a 
rod,  its  material  and  subdivision  are  dependent  on  the  use  for 
which  it  is  designed,  as  a  metal  scale  lends  itself  more  readily  to 
permanent  and  accurate  graduation,  and  is  less  susceptible  to 
change  with  time  and  temperature ;  the  latter  condition,  in  fact, 
may  be  accurately  and  satisfactorily  accounted  for  by  knowing 
the  coefficient  of  expansion  of  the  bar  and  the  temperature  at 
which  it  is  used.  The  tape  may  be  either  of  metal  or  linen, 
and  is  a  convenient  measure  for  many  purposes.  There  are  also 
constructed  meter  scales,  half-meter  scales,  double  and  single 
decimeter  scales,  the  shape  and  material  as  well  as  the  accuracy 
of  graduation  depending  on  the  purposes  for  which  they  are  to 
be  used.  When  it  comes  to  the  division  of  millimeters  it  is 
necessary  to  employ  a  dividing  engine,2  and  the  finest  scales  are 
ruled  on  glass  or  upon  a  smooth  and  even  substance,  such  as 
speculum  metal  platinum-iridium,  or  nickel  steel.  The  glass 
scales  are,  of  course,  to  be  used  with  the  microscope,  and  similar 
scales  can  be  constructed  photographically  by  reducing  in  a 
desired  proportion. 

1  There  are  also  standard  bars  used  in  the  most  refined  base  measurements,  such 
as  that  at  Holton,  Mich.,  which  was  of  5  meters  length.     These  bars  require  the 
most  careful  levelling,  are  packed  in  ice  at  the  time  of  making  the  measurement, 
and  are  only  used  when  the  greatest  accuracy  is  desired,  as  the  refinements  of  a 
laboratory  are  involved  in  a  field  operation.     See  Woodward,  "The  iced  bar  and 
long  tape  base  apparatus  and  the  results  of  measures  made  with  them  on  the 
Holton  and  St.  Albans  bases,"  part  ii.  of  Appendix  No.  8  of  Report  of  United 
States  Coast  and  Geodetic  Survey  for  1892,  pp.  334-489.      Professor  Woodward 
also  discusses  "Long  Steel  Tapes"  in  a  paper  presented  to  the  International 
Engineering  Congress  of  1893,  and  printed  in  the  Transactions  of  the  American 
Society  of  Civil  Engineers,  vol.  xxx.  p.  81. 

2  See  chapter  x. — Standards  and  Comparison,  p.  225. 


142     EVOLUTION   OF   WEIGHTS   AND   MEASURES 

Measures  of  Surface. 

Number  of  Square 
Abbreviation.  Meters. 

Square  kilometer,  km2.  1,000,000m2. 

Hectar  (square  hectometer),  ha.  —  hm2.  10,000m2. 

Ar  (square  decameter),    -'  :              a. —  dm'2.  100m2. 

Centiar  or  square  meter,  ca.  or  m2.  1m2. 

Square  decimeter,  dm2.  -01  m2. 

Square  centimeter,  cm2.  *0001m2. 

Square  millimeter,  mm2.  '000,001m2. 

For  the  measurement  of  surfaces  it  is  customary  to  employ 
as  a  unit  a  square  or  quadrilateral  figure  bounded  by  four  equal 
sides  at  right  angles  to  each  other.  In  such  a  unit  the  sides  are 
usually  made  equal  to  the  linear  unit,  hence  in  the  metric  system 
a  square  of  this  nature  would  have  for  each  side  a  meter,  and 
would  be  known  as  a  square  meter,  forming  the  principal  unit 
for  the  measurement  of  surface.  The  next  greater  unit  would  be 
formed  by  a  square  whose  bounding  sides  were  each  equal  to  a 
decameter,  and  consequently  would  include  100  of  the  principal 
units.  If  our  units  of  length  increase  by  a  ratio  of  10,  it  is 
obvious  that  the  unit  of  surface  based  on  these  same  units  of 
length  must  increase  by  the  square  of  10  or  by  100  as  is  indicated 
by  the  table.  The  same  nomenclature  is  retained,  but  the  word 
square  is  prefixed,  and  in  the  case  of  the  units  formally  adopted 
for  the  measure  of  land,  the  terms  hectar  and  ar  have  been 
selected  to  designate  respectively  the  square  hectometer  and  the 
square  decameter.  In  writing  and  converting  the  measures  of 
area  it  is  necessary  to  multiply  or  divide  by  100  when  changing 
to  a  larger  or  smaller  unit,  consequently  in  the  decimal  fraction 
each  metric  unit  must  be  given  two  places  of  figures.  For 
example,  to  write  as  square  meters  984'8963  square  decimeters,  it 
would  be  necessary  to  move  the  point  two  places  to  the  left  and 
we  would  have  9*848963  square  meters,  which  also  could  be 
written  9  square  meters,  84  square  decimeters,  89  square  centi- 
meters and  63  square  millimeters,  or  even  9848963  square  milli- 
meters if  it  was  so  desired.  The  square  kilometer  is  employed 
in  topographical  work  on  a  large  scale,  or  in  cartography  in 
summing  up  the  area  of  a  country  or  large  region.  For  fields 


THE   METRIC   SYSTEM   OF  TO-DAY  143 

the  hectar  is  used,  and  is  parallel  to  the  acre,  which  contains 
•4047  hectars.  For  land  of  smaller  dimension,  such  as  city  lots, 
it  is  customary  to  use  the  are.  The  measurement  of  surfaces,  as 
of  walls  by  the  painter  or  paperhanger,  or  of  floors  by  the  dealer 
in  carpets,  is  naturally  made  by  the  square  meter.  Such  measure- 
ments as  the  square  decimeter  and  the  square  centimeter  are- 
useful  for  purposes  that  will  naturally  suggest  themselves,  but 
again  attention  may  be  called  to  the  fact  that  scientific  men 
prefer  to  use  the  square  centimeter  and  the  cubic  centimeter 

also  as  much  as  possible. 

i 

Measures  of  Volume. 

The  volume  of  a  body,  or  the  amount  of  space  that  it  occupies, 
is  usually  measured  by  a  unit  known  as  a  cube,  which  is  a 
parallelopipedon  bounded  by  six  equal  squares.  In  the  metric 
system  the  principal  unit  is  the  cubic  meter,  a  cube  each  of 
whose  faces  is  a  square  meter,  and  consequently  whose  edges  are 
each  a  meter  in  length.  The  cubic  meter  is  the  largest  unit  of 
volume  in  the  metric  system,  though  logically  there  is  no  reason 
why  cubic  decameters,  hectometers,  and  kilometers  should  not  be 
employed  were  there  any  necessity  for  their  use,  which  there  is 
not.  Therefore  we  have  only  to  concern  ourselves  with  the  sub- 
multiples  of  the  cubic  meter.  On  the  decimal  principle  the 
next  smaller  unit  must  be  one  in  which  the  size  is  determined 
by  the  tenth  of  the  meter,  or  the  decimeter,  or  a  cube  each  of 
whose  edges  is  a  decimeter.  Obviously,  to  make  a  cubic  meter 
ten  rows  of  these  cubes,  arranged  so  that  they  are  ten  in 
length,  will  have  to  be  placed  ten  deep,  or  one  thousand  of  our 
cubic  decimeters  must  be  used.  So  that  where  the  unit  of  area 
required  a  ratio  of  100  to  pass  from  a  smaller  to  a  greater,  the 
units  of  volume  need  a  ratio  of  1000  ;  that  is,  three  figures  of 
integers  or  of  the  decimal  fraction  are  required  for  each  unit. 
Thus  a  cubic  meter  will  contain  1000  cubic  decimeters,  or 
1  000  000  cubic  centimeters,  or  1  000  000  000  cubic  millimeters. 
We  may  read  76-8546732  cubic  meters  as  76854*673  cubic 
centimeters,  or,  were  it  desirable,  76  854  673  cubic  millimeters. 
Or  we  could  read  the  above  expression  as  76  .cubic  meters,. 
854  cubic  decimeters,  and  673  cubic  centimeters. 


144     EVOLUTION   OF   WEIGHTS   AND   MEASURES 

The  cubic  meter  is  employed  in  all  cases  where  any  con- 
siderable quantity  of  a  substance  must  be  considered.  Thus 
the  amount  of  material  excavated  from  a  foundation,  railway 
cut,  or  canal,  would  be  expressed  in  cubic  meters,  as  would  be 
blocks  of  marble  or  the  contents  of  a  tank  or  reservoir.  When 
the  cubic  meter  is  applied  to  the  measurement  of  firewood  it 
receives  a  new  name,  stere  ( =  35*317  cubic  feet  or  "27  cord),  and 
as  a  pile  of  wood  can  be  divided  or  increased  readily,  the  name 
of  decistere  is  given  to  the  one-tenth  part,  and  that  of  decastere  to 
ten  times  the  unit  quantity.  The  cubic  decimeter  is  an  inter- 
mediate unit  like  the  corresponding  decimeter  and  square 
decimeter,  but  it  possesses  importance,  inasmuch  as  it  is  the 
volume  of  the  liter  (very  nearly),  and  as  such  is  frequently 
employed  in  calculations  where  it  is  desired  to  obtain  the 
capacity  of  a  given  space,  as  will  be  explained  further  on  under 
measures  of  capacity.  The  cubic  centimeter  answers  for  many 
purposes,  and  is  the  usual  unit  for  scientific  work.  Thus  in 
pharmacy  by  the  volumetric  method  (see  page  194)  almost  all 
liquids  are  compounded  by  taking  the  desired  quantities  in  cubic 
centimeters,  while  to  determine  standard  pressure  reference  is 
made  to  that  of  a  column  of  75  cubic  centimeters  of  mercury  at 
0°  centigrade. 

Measures  of  Capacity. 

Hectoliter,  -  hi.  100  liters. 

Decaliter,    -  dal.  10  liters. 

Liter,  1. 

Deciliter,  '  -  dl.  '1  liter. 

Centiliter,   -  cl.  *01  liter. 

Milliliter,    -  ml.  '001  liter. 

The  close  connection  between  measures  of  volume  and  capacity 
is  obvious,  and  the  founders  of  the  metric  system  took  as  their 
unit  of  capacity  the  volume  of  a  cubic  decimeter.  Subsequent 
measures  of  the  kilogram,  and  the  .mass  of  water  necessary  to 
amount  to  this  weight,  resulted  in  the  conclusion  that  for  strictly 
scientific  purposes  this  was  inaccurate,  and  consequently  the  legal 
definition  is  in  the  words  of  the  International  Committee,  "  The 
liter  is  the  volume  occupied  by  the  mass  one  kilogram  of  pure 


THE   METRIC   SYSTEM   OF  TO-DAY  145 

water  at  its  maximum  density  and  under  normal  atmospheric 
pressure,"  and  this  decision  was  duly  sanctioned  by  the  general 
conference  of  1901.  As  the  result  of  a  large  number  of  careful 
experiments  it  was  found  that  a  mean  value  for  the  mass  of  a 
cubic  decimeter  of  water  at  4  degrees  centigrade  (its  temperature 
of  maximum  density)  would  be  '999974  kilogram,  and  that  the 
error  of  assuming  the  liter  equal  to  the  cubic  decimeter  would  be 
only  about  one  part  in  30,000,  an  amount  only  appreciable  in  the 
most  refined  measurements.  The  liter  is  subdivided  on  a 
decimal  basis,  while  its  multiples  are  similarly  arranged,  and 
from  what  has  preceded  it  will  be  possible  to  understand  the 
various  units  merely  by  referring  to  the  table.  In  actual  practice 
the  liter  and  the  hectoliter  are  the  units  chiefly  employed,  as  for 
many  reasons  it  is  preferable  to  employ  cubic  centimeters  for 
smaller  measures,  while  the  decaliter,  being  an  intermediate 
measure,  does  not  come  into  wide  use.  The  liter  and  all  the 
measures  of  capacity  are  used  for  both  dry  and  liquid  substances ; 
but  it  is  a  tendency  of  modern  metrology  quite  independent  of 
the  metric  system  to  do  away  so  far  as  possible  with  dry 
measures  of  capacity  and  buy  and  sell  such  substances  by  weight.1 
The  liter,  however,  can  be  used  to  measure  all  liquids  (such  as 
water,  milk,  wine,  beer,  oil,  etc.),  vegetables,  grains,  seeds,  etc.,  in 
ordinary  retail  transactions.  When  large  quantities  of  the 
commodity  are  dealt  in  or  discussed,  then  it  is  customary  to  use 
hectoliters.  The  liter  corresponded  so  closely  to  the  ancient 
French  pinte  ('981  liter)  which  it  supplanted  that  its  use  did  not 
occasion  any  difficulty,  and  as  it  is  intermediate  in  value  between 
the  American  dry  ( =  M012  liter)  and  liquid  quarts  (  =  '94636 
liter)  its  employment  would  result  in  a  simplification  of  measures, 
and  would  involve  no  inconvenience. 

The  adoption  of  metric  measures  of  capacity  in  the  United 
States  would  result  in  important  simplifications,  as  the  present 
measures  differ  from  those  of  Great  Britain,  and  possess  no 
intrinsic  merits  of  their  own.  In  fact,  in  the  Anti-metric 
Argument  of  the^Committee  of  the  American  Society  of  Mechanical 
Engineers  (vol.  xxiv.  New  York,  1902),  which  opposes  most 
bitterly  any  attempt  at  the  introduction  of  the  metric  system,  it 
is  stated  (p.  676),  "  That  there  is  no  reason  for  the  English 

1  In  Europe  the  practice  of  selling  liquids  by  weight  is  also  increasing. 

K 


146     EVOLUTION   OF   WEIGHTS   AND   MEASURES 


system  retaining  the  gallon  and  the  bushel  except  that  they  are 
in  such  common  use.  For  convenience  in  computation  it  would 
be  well  if  the  gallon  were  216  cubic  inches,  or  the  cube  of  6 
inches,  and  the  bushel  1728  cubic  inches,  or  1  cubic  foot." 

In  constructing  the  actual  measures  of  capacity  their  range  is 
extended  by  binary  subdivision  and  doubling,  so  that  all  possible 
capacities  can  be  measured  and  substances  sold  on  a  basis  of  the 
simplest  mental  process,  namely,  that  of  halving.  Actual  measures 
in  the  form  of  wooden  vessels  for  measuring  grain  with  a  capacity 
of  one  hectoliter  and  less  are  constructed  with  their  internal 
height  and  diameter  equal,  while  for  measuring  liquors,  wines, 
and  alcohol,  the  French  laws  provide  that  the  internal  height 
should  be  twice  the  internal  diameter.  Oil  and  milk  measures 
are  of  tin,  and  their  internal  height  and  diameter  are  equal. 


, 


Measures  of  Mass. 


Metric  ton, 

t.       10  Quintals 

Quintal, 

q.      10  My  r  iag  ra  m  s 

Myriagram, 

10  Kilograms 

Kilogram, 

kg.    10  Hectograms 

Hectogram, 

10  Decagrams 

Decagram, 

10  Grams 

Gram, 

g.      10  Decigrams 

Decigram, 

dg.    10  Centigrams 

Centigram, 

eg.    10  Milligrams 

Milligram, 

mg. 

1000  Kilograms  1,000,000  grams 


100 
10 


100,000 

10,000 

1,000 

100 

10 

1 

•1 

•01 

•001 


10«g. 
105g. 


103g. 
102g. 
lOg. 

g- 


10  - 


By  mass  is  meant  the  actual  quantity  of  matter  which  a  body 
contains,  and  it  is  to  be  distinguished  from  weight,  which  is  the 
force  with  which  a  body  is  attracted  to  the  earth.  Now,  as  this 
force  of  attraction  depends  upon  the  mass  of  a  body,  it  follows 
that  the  weight  of  different  bodies  at  the  same  place  is  pro- 
portional to  their  respective  masses.  But  as  the  force  of 
attraction  or  gravity  varies  at  different  points  on  the  earth's 
surface,  it  is  obvious  that  bodies  of  the  same  mass  will  have 
different  weights  at  different  places.  Originally,  as  we  have 
seen,  the  gram  was  defined  by  the  decree  of  18  Germinal,  year 
III.,1  as  "  The  absolute  weight  of  a  volume  of  pure  water  equal  to 
a  cube  of  the  one-hundredth  part  of  a  meter  and  at  the  temperature 

1  See  p.  54. 


THE   METRIC   SYSTEM   OF  TO-DAY  147 

of  melting  ice,"  and  on  this  basis  the  Kilogram  of  the  Archives 
was  constructed.  However,  after  the  construction  of  the  Inter- 
national standard  kilogram  it  was  deemed  desirable  to  define 
formally  the  kilogram,  and  at  a  meeting  of  the  International 
Committee  on  October  15,  1889,  it  was  decided  that  "The  mass 
of  the  international  kilogram  is  taken  as  unity  for  the  inter- 
national system  of  weights  and  measures,"  and  this  decision  was 
confirmed  at  the  third  general  conference  held  at  Paris  in  1901. 
While  the  gram  is  the  fundamental  unit  of  mass,  yet  in  actual 
practice,  as  in  the  construction  of  the  standard,  it  has  been  found 
rather  small  for  most  weighings,  and  consequently  the  kilogram 
is  employed  as  a  practical  unit. 

There  is,  of  course,  the  same  wide  range  of  units  of  weights  as 
in  other  classes  of  measures,  and  on  precisely  the  same  decimal 
basis,  as  the  table  plainly  sets  forth.  The  same  considerations 
govern  their  use,  and  we  find  that  the  number  of  units  in  actual 
use  is  but  a  small  part  of  those  available.  Thus,  for  large 
weights  the  metric  ton  is  the  unit  employed,  and  is  used  in  the 
weighing  of  ore,  coal,  hay,  and  other  substances  dealt  in  in 
large  quantities.  It  is  employed  in  estimating  the  mineral  pro- 
duction of  the  world,  being  a  convenient  weight  to  which  the 
output  of  different  nations  may  best  be  reduced  for  purposes  of 
comparison  and  statistical  study.  It  corresponds  so  closely  with 
the  long  ton  of  2240  pounds  (a  metric  ton  equals  2204*62  Ibs.) 
that  for  many  purposes  it  is  practically  equivalent.  The  quintal 
has  the  same  line  of  uses  as  the  hundredweight,  which  either 
as  112  pounds  or  100  pounds  is  still  employed  in  some  branches 
of  trade.  It  would  be  substantially  equivalent  to  twice  the 
former,  and  would  not  vary  greatly  from  the  American  barrel  of 
flour,  which  contains  196  pounds  net. 

The  myriagram  is  rarely,  if  ever,  used,  but  the  kilogram  is  a 
unit  which  is  found  universally.  Being  the  weight  of  a  cubic 
decimeter  of  water  it  enables  one  instantly  to  determine  the 
weight  of  a  body  whose  volume  and  specific  gravity  are  known, 
and  for  that  reason  is  very  convenient  in  calculation,  such  as  to 
determine  the  weight  of  cut  stone,  etc.  It  is  the  unit  most 
frequently  employed  in  trade  and  industry  for  the  sale  of 
merchandise  of  all  descriptions.  By  using  the  half  kilogram 
there  is  a  weight  which  approximates  the  pound,  and  being 


146     EVOLUTION   OF   WEIGHTS   AND   MEASURES 


system  retaining  the  gallon  and  the  bushel  except  that  they  are 
in  such  common  use.  For  convenience  in  computation  it  would 
be  well  if  the  gallon  were  216  cubic  inches,  or  the  cube  of  6 
inches,  and  the  bushel  1728  cubic  inches,  or  1  cubic  foot." 

In  constructing  the  actual  measures  of  capacity  their  range  is 
extended  by  binary  subdivision  and  doubling,  so  that  all  possible 
capacities  can  be  measured  and  substances  sold  on  a  basis  of  the 
simplest  mental  process,  namely,  that  of  halving.  Actual  measures 
in  the  form  of  wooden  vessels  for  measuring  grain  with  a  capacity 
of  one  hectoliter  and  less  are  constructed  with  their  internal 
height  and  diameter  equal,  while  for  measuring  liquors,  wines, 
and  alcohol,  the  French  laws  provide  that  the  internal  height 
should  be  twice  the  internal  diameter.  Oil  and  milk  measures 
are  of  tin,  and  their  internal  height  and  diameter  are  equal.  . 

Measures  of  Mass. 

1000  Kilograms  1,000,000  grams  106g. 

100          „               100,000       „  105g. 

10          „                 10,000    -  „  104g. 

1,000       „  103g. 

100       „  102g. 

10       „  lOg. 

1    „        g. 

•i     „      lo-'g. 
•01     „      io-*g. 

•001       „        10~3g. 

By  mass  is  meant  the  actual  quantity  of  matter  which  a  body 
contains,  and  it  is  to  be  distinguished  from  weight,  which  is  the 
force  with  which  a  body  is  attracted  to  the  earth.  Now,  as  this 
force  of  attraction  depends  upon  the  mass  of  a  body,  it  follows 
that  the  weight  of  different  bodies  at  the  same  place  is  pro- 
portional to  their  respective  masses.  But  as  the  force  of 
attraction  or  gravity  varies  at  different  points  on  the  earth's 
surface,  it  is  obvious  that  bodies  of  the  same  mass  will  have 
different  weights  at  different  places.  Originally,  as  we  have 
seen,  the  gram  was  defined  by  the  decree  of  18  Germinal,  year 
III.,1  as  "  The  absolute  weight  of  a  volume  of  pure  water  equal  to 
a  cube  of  the  one-hundredth  part  of  a  meter  and  at  the  temperature 

1  See  p.  54. 


Metric  too, 

t. 

10  Quintals 

Quintal, 

q- 

10  Myriagrams 

Myriagram, 

10  Kilograms 

Kilogram, 

kg. 

10  Hectograms 

Hectogram, 

10  Decagrams 

Decagram, 

10  Grams 

Gram, 

S- 

10  Decigrams 

Decigram, 

dg. 

10  Centigrams 

Centigram, 

eg. 

10  Milligrams 

Milligram, 

mg. 

— 

THE   METRIC   SYSTEM   OF  TO-DAY  147 

of  melting  ice,"  and  on  this  basis  the  Kilogram  of  the  Archives 
was  constructed.  However,  after  the  construction  of  the  Inter- 
national standard  kilogram  it  was  deemed  desirable  to  define 
formally  the  kilogram,  and  at  a  meeting  of  the  International 
Committee  on  October  15,  1889,  it  was  decided  that  "The  mass 
of  the  international  kilogram  is  taken  as  unity  for  the  inter- 
national system  of  weights  and  measures,"  and  this  decision  was 
confirmed  at  the  third  general  conference  held  at  Paris  in  1901. 
While  the  gram  is  the  fundamental  unit  of  mass,  yet  in  actual 
practice,  as  in  the  construction  of  the  standard,  it  has  been  found 
rather  small  for  most  weighings,  and  consequently  the  kilogram 
is  employed  as  a  practical  unit. 

There  is,  of  course,  the  same  wide  range  of  units  of  weights  as 
in  other  classes  of  measures,  and  on  precisely  the  same  decimal 
basis,  as  the  table  plainly  sets  forth.  The  same  considerations 
govern  their  use,  and  we  find  that  the  number  of  units  in  actual 
use  is  but  a  small  part  of  those  available.  Thus,  for  large 
weights  the  metric  ton  is  the  unit  employed,  and  is  used  in  the 
weighing  of  ore,  coal,  hay,  and  other  substances  dealt  in  in 
large  quantities.  It  is  employed  in  estimating  the  mineral  pro- 
duction of  the  world,  being  a  convenient  weight  to  which  the 
output  of  different  nations  may  best  be  reduced  for  purposes  of 
comparison  and  statistical  study.  It  corresponds  so  closely  with 
the  long  ton  of  2240  pounds  (a  metric  ton  equals  2204*62  Ibs.) 
that  for  many  purposes  it  is  practically  equivalent.  The  quintal 
has  the  same  line  of  uses  as  the  hundredweight,  which  either 
as  112  pounds  or  100  pounds  is  still  employed  in  some  branches 
of  trade.  It  would  be  substantially  equivalent  to  twice  the 
former,  and  would  not  vary  greatly  from  the  American  barrel  of 
flour,  which  contains  196  pounds  net. 

The  myriagram  is  rarely,  if  ever,  used,  but  the  kilogram  is  a 
unit  which  is  found  universally.  Being  the  weight  of  a  cubic 
decimeter  of  water  it  enables  one  instantly  to  determine  the 
weight  of  a  body  whose  volume  and  specific  gravity  are  known, 
and  for  that  reason  is  very  convenient  in  calculation,  such  as  to 
determine  the  weight  of  cut  stone,  etc.  It  is  the  unit  most 
frequently  employed  in  trade  and  industry  for  the  sale  of 
merchandise  of  all  descriptions.  By  using  the  half  kilogram 
there  is  a  weight  which  approximates  the  pound,  and  being 


148     EVOLUTION   OF   WEIGHTS   AND   MEASURES 

slightly  larger  there  is  an  element  in  favor  of  the  purchaser. 
Instead  of  using  hectograms  and  decagrams  it  is  found  more 
convenient  to  express  such  quantities  in  terms  of  fractions  of 
kilograms  or  as  grams,  and  such  is  the  usual  practice.  The  gram 
is  extensively  employed  in  science,  as  by  the  chemist,  and  by 
those  dealing  in  small  and  valuable  materials,  as  jewellers  and 
coiners.  In  multiples  of  ten  it  affords  a  convenient  substitute 
for  the  ounce,  30  grams  (28*3495  exactly)  corresponding  to  one 
ounce  avoirdupois.  Its  relation  to  the  cubic  centimeter  of  water 
makes  it  a  useful  unit  for  the  physicist  or  chemist,  and  unless 
there  is  reason  to  the  contrary  it  is  always  used  to  record  and 
describe  the  results  of  his  experimental  and  other  work.  As  the 
gram  is  so  constantly  used  for  measures  of  weight  of  this  nature 
by  those  having  to  do  with  masses  of  a  size  convenient  for  its 
use  the  adoption  of  this  part  of  the  metric  system  would  work  no 
hardship,  as  apothecaries'  weight,  which  it  would  supplant,  has  few 
defenders,  and  is  destined  to  disappear.  Decigrams,  centigrams, 
and  milligrams  are  used  in  the  form  of  fractions  of  the  gram, 
though  milligrams  are  employed  to  a  certain  extent,  especially  as 
the  riders  or  smallest  weights  of  a  fine  balance  enable  weighings 
to  be  made  in  milligrams  and  fractions  of  a  milligram. 

In  the  actual  weights  there  is  not  only  the  diversity  indicated 
by  the  table,  but  also  others  obtained  by  doubling  or  halving  the 
various  units  there  mentioned.  The  construction  and  design  of 
these  weights  as  also  their  accuracy  depends  upon  the  purpose 
for  which  they  are  intended,  and  vary  from  the  platinum  iridium 
and  rock  crystal  copies  of  the  international  standard  down  to  the 
cast-iron  weights  of  the  retail  dealer.  The  cast-iron  weights 
range  from  50  kilograms  to  50  grams  or  \  hectogram,  while  the 
brass  weights,  which  are  usually  cylindrical  in  shape,  with  the 
upper  part  fashioned  into  a  knob  for  more  convenient  handling, 
range  from  20  kilograms  to  1  gram.  Fractions  of  a  gram  are 
usually  made  of  sheet  metal,  such  as  platinum,  german  silver,  or 
aluminium,  as  in  this  shape  they  are  more  readily  handled  with 
the  forceps  employed  to  transfer  them  from  their  case  to  the 
pans  of  the  balance.  The  very  smallest  or  milligram  weights  are 
known  as  "riders,"  and  are  twisted  loops  of  wire  which  may  be 
placed  at  any  desired  position  along  the  graduated  beam  of  the 
balance,  and  thus  enable  the  observer  to  read  to  fractions. 


THE   METRIC   SYSTEM   OF  TO-DAY  149 

While  there  have  been  enumerated  under  each  class  of 
measures  a  number  of  units,  yet  it  is  necessary  to  state  again  that 
only  a  comparatively  small  number  are  employed.  In  this 
respect  the  metric  system  is  similar  to  the  United  States 
monetary  system,  where  there  are  mills,  dimes,  and  eagles,  as  well 
as  quarters  and  halves,  in  addition  to  dollars  and  cents,  but  in 
computation  everything  settles  down  to  a  dollars  and  cents  basis. 
This  is  precisely  the  case  with  the  metric  system,  and  while  the 
intermediate  units  appear  in  the  tables  we  have  taken  care  to 
explain  how  infrequently  they  are  employed.  In  fact,  it  is  a 
tendency  in  metrology  to  eliminate  from  use  as  many  units  as 
possible,  and  all  existing  measures  are  on  a  far  less  liberal  scale 
in  point  of  numbers  than  those  of  a  century  ago,  not  to  speak  of 
those  of  ancient  times  or  of  the  middle  ages.  With  the  metric 
system  this  elimination  can  be  done  without  any  trouble,  as  it  is 
the  work  of  but  a  moment  to  change  from  one  unit  to  another 
for  any  purpose  whatsoever. 


152     EVOLUTION   OF   WEIGHTS   AND   MEASURES 

of  units  is  employed,  and  this  system,  based  on  the  metric 
units,  was  developed  in  Great  Britain,  and  has  been  adopted  by 
scientists  and  engineers  universally.  When  great  industries 
were  established  to  apply  to  the  everyday  uses  of  mankind  the 
discoveries  and  inventions  of  men  of  science  in  this  field,  these 
same  units  were  retained,  and  were  later  sanctioned  by  inter- 
national agreements.  No  voice  has  ever  been  heard  to  dispute 
the  advantages  of  such  a  system,  and  the  result  has  been  that 
there  has  been  more  progress  in  electricity  through  the  inter- 
change of  ideas  than  in  any  other  branch  of  applied  science. 
When  electrical  congresses  meet  every  communication  is  in- 
telligible at  once  to  every  member  so  far  as  the  expression 
of  quantities  goes.  When  tenders  are  asked  for  electrical 
machinery,  materials,  or  apparatus,  the  manufacturers  of  every 
nation  of  the  world  are  on  the  same  footing  as  regards  under- 
standing the  specifications  and  utilizing  materials  for  a  desired 
output.  Accuracy  in  measurement  is  not  restricted  to  any 
single  nation  or  its  scientific  workers,  as  the  work  of  the  latter 
can  be  put  immediately  at  the  disposal  of  the  .  world,  and  the 
highest  precision  can  be  secured  by  joint  effort  and  co-operation. 
In  fact,  when  the  Physicalisch-Technische  Eeichsanstalt  at  Char- 
lottenburg,  near  Berlin,  was  the  only  important  governmental 
testing  bureau  and  physical  laboratory,  it  received  apparatus  and 
materials  from  many  nations  outside  of  Germany  to  be  examined 
and  standardized  according  to  the  common  system.  To-day  elec- 
trical measuring  instruments  certified  to  by  the  Reich sanstalt,  the 
Laboratoire  Central  d'Electricite  at  Paris,  the  National  Physical 
Laboratory  of  England,  or  the  U.S.  Bureau  of  Standards,  can  be 
used  for  electrical  measurements  anywhere  in  the  world,  as  the 
units  employed  depend  for  their  derivation  on  the  same  defini- 
tions. In  fact,  so  much  a  matter  of  course  is  the  single  system 
of  electrical  units  that  no  one  would  think  of  proposing  any  other, 
and  its  existence  is  so  taken  for  granted  that  its  advantages  are 
rarely  spoken  of  or  even  considered  until  the  possible  chaos  of  sub- 
stituting a  number  of  systems  in  its  place  is  mentioned.  Indeed^ 
while  the  various  units  are  frequently  criticized,  no  electrician 
or  physicist  would  venture  to  propose  the  adoption  of  new  units 
locally,  despite  the  fact  that  universal  reforms  in  units  and 
standards  are  advocated  before  international  congresses. 


THE   METRIC   SYSTEM   FOR   COMMERCE        15S 

Looking  at  the  question  of  weights  and  measures  from  a 
strictly  commercial  standpoint  it  is  clear  that,  as  commerce 
involves  primarily  the  exchange  of  quantities  of  various  com- 
modities, the  use  of  a  simple  and  convenient  method  for  the 
rapid  calculation  of  weight,  length,  and  capacity  must  promote 
ease  and  security  of  commercial  intercourse.  The  metric  system 
being  decimal,  and  consequently  the  most  easily  grasped  and 
applied,  is  therefore  the  best  for  commerce,  and  when  to  this 
is  coupled  the  fact  that  its  use  is  all  but  universal  and  is  em- 
ployed in  the  major  portion  of  international  commercial  trans- 
actions, it  is  easy  to  see  that  a  great  saving  of  time  in  business 
operations  must  result  from  its  adoption.  That  this  saving  of 
time  and  simplicity  is  real,  and  not  the  mere  hope  or  opinions 
of  reformers,  can  be  demonstrated  by  reference  to  the  reports  of 
American  and  British  consular  and  diplomatic  officials  who  are 
acquainted  with  both  the  Anglo-Saxon  and  the  metric  systems. 
These  reports,  notable  among  which,  as  being  most  comprehen- 
sive and  complete,  are  those  presented  to  Parliament  in  1900 
and  190 1,1  to  which  reference  has  already  been  made,  speak 
emphatically  in  this  respect,  and  in  a  communication  from 
Portugal  appears  the  statement  that  "  The  large  amount  of  time 
saved  in  commercial  houses  by  the  simplicity  of  the  metric 
system,  as  well  as  by  the  uniformity  now  existing  in  place  of 
the  former  chaos,  is  in  itself  a  valuable  factor  in  considering 
the  advantages  of  the  new  system." 2 

The  successful  prosecution  of  foreign  commerce  requires  a 
complete  understanding  between  merchants  in  different  countries 
as  to  each  other's  standing,  methods  of  payment,  and,  most 
important,  as  to  the  goods  themselves  which  form  the  subject  of 
the  transaction.  Aside  from  standards  of  quality,  quantities  and 
dimensions  must  be  considered,  and  it  is  here  that  universal 
measures  and  standards  are  needed.  It  is  also  of  importance  for 
both  buyer  and  seller  to  know  the  quantity  of  the  commodity  in 
existence  at  different  places,  the  quantity  produced  and  consumed 
in  previous  years,  and  other  statistical  information.  As  regards 

1  English  Parliamentary  Accounts  and  Papers;  1900,  vol.  xc. ;  Reports  from  Her 
Majesty'*   Representative,*  in  Europe  on  the  Metric   System:    1901,    vol.    Ixxx. ;, 
Reports  on  Metric  System,  part  ii. 

2  Ibid,  part  i.  p.  54. 


154     EVOLUTION   OF   WEIGHTS   AND   MEASURES 

the  latter,  it  will  readily  be  seen  that  the  collection  and  diffusion 
of  such  knowledge  would  be  facilitated  if  the  same  units  were 
used  in  every  country  and  port  of  the  globe,  and  trade  could  then 
be  carried  on  in  a  more  intelligent  manner,  and  with  the  elimina- 
tion of  speculative  elements,  while  tariff  laws  and  custom  regula- 
tions, etc.,  could  be  more  intelligently  framed  through  the  better 
and  more  uniform  character  of  the  statistical  information.  Such 
benefits  accrue  to  trade  throughout  the  world  generally,  and  are 
generally  recognized. 

But  with  no  uniform  system  of  weights  and  measures  which 
may  be  applied  to  the  description  of  goods,  it  is  inevitable  that 
there  is  a  lack  of  clear  understanding  between  buyer  and  seller, 
and  one  of  these  parties  is  at  a  disadvantage.  Especially  is  this 
true  if  there  is  a  competitor  who  is  ready  to  trade  on  a  basis  more 
readily  understood.  Thus,  if  a  man  is  in  doubt  as  to  certain 
•elements  concerning  goods  which  he  desires  to  buy  or  sell,  he 
naturally  assumes  that  there  are  other  points  about  which  he  is 
•equally  ignorant,  and  consequently  he  is  unwilling  to  undertake 
the  transaction.  True,  he  may  compute  in  his  own  system  the 
quantities  or  dimensions  of  the  article  or  articles,  or  may  receive 
these  figures  in  whole  or  in  part  from  the  other  merchant  or 
agent ;  but  the  basis  of  trade  is  unsatisfactory,  and  it  is  natural 
for  men  to  buy  or  sell  according  to  their  usual  measurements  even 
if  the  goods  must  be  imported  from  a  greater  distance.  This, 
furthermore,  is  emphasized  by  the  extensive  use  of  standards 
which,  at  first  designed  for  a  single  country  and  trade,  have 
gradually  crept  abroad  so  that  if  either  English  or  Continental 
goods,  such  as  pipe  or  nuts  and  bolts,  for  example,  have  secured 
a  foothold  in  a  certain  country,  it  is  quite  certain  that  in  all 
subsequent  orders  they  will  be  demanded,  and  a  newcomer  in  the 
field  will  have  to  conform  to  styles  and  standards  already  estab- 
lished. Thus  to  compel  trade  in  a  large  and  unusual  number  of 
sizes  is  a  most  wasteful  economic  process,  and  results  in  forcing 
the  manufacture  into  the  hands  of  a  comparatively  small  number 
of  producers,  who  can  so  control  their  business  as  to  occupy 
certain  fields  exclusively  rather  than  to  establish  wholesome 
competition  between  all  the  manufacturers  of  the  world. 

A  striking  example  of  the  evils  attending  lack  of  standardiza- 
tion in  measures,  materials,  and  machinery,  is  to  be  found  in 


THE   METRIC   SYSTEM   FOR   COMMERCE        155 

the  mining  districts  of  South  Africa,  where  mining  and  other 
engineering  operations  are  carried  on  in  a  cosmopolitan  manner 
by  engineers  from  various  countries.  Machinery  and  supplies  are 
imported,  for  specific  purposes,  from  all  over  the  world,  and  con- 
sequently they  vary  in  dimensions,  often  in  parts  that  properly 
should  be  interchangeable.1  The  result  is  that  considerable  fitting 
is  required  in  order  to  make  the  various  parts  of  a  plant  work 
harmoniously.  This  of  course  involves  time  and  expense  without 
accompanying  benefit  to  anyone,  whereas  by  a  system  of  inter- 
national standards  such  waste  would  be  avoided.  Furthermore, 
a  proper  system  of  standardization  would  enable  the  specifications 
of  machinery  and  supplies  to  be  prepared  in  such  a  way  that 
manufacturers  and  dealers  would  know  exactly  what  was  wanted, 
and  make  their  bids  accordingly,  to  the  benefit  of  all  concerned. 
If  the  standardization  was  universal  a  simple  description  of  the 
desired  articles  could  be  circulated,  and  manufacturers  and  dealers 
all  over  the  world  could  submit  prices  and  estimates.  Thus  the 
whole  world  could  participate  in  the  competition,  and  not  only 
would  the  supplies  be  cheaper  to  the  purchaser,  but  manufacturing 
and  commerce  would  be  stimulated. 

Now,  the  first  principle  of  standardization  is  the  defining  of 
sizes  in  a  regular  and  systematic  manner,  and  conforming  to  a 
permanent  standard,  and  this  in  the  ultimate  analysis  must 
depend  on  a  standard  of  length  or  mass.  Consequently,  if  the 
dimensions  of  articles  are  referred  to  one  and  the  same  system, 
and  that  the  international  or  metric  system,  it  is  comparatively 
simple  to  reach  a  point  where  all  articles  of  a  class  are  reduced  to 
certain  sizes  determined  by  conference  and  mutual  consent  of  the 
makers  and  consumers  of  the  commodities  in  question.  There  is, 
in  short,  a  survival  of  the  fittest  and  most  convenient  sizes,  and 
machinery  and  materials,  involved  in  making  the  various  articles, 
are  soon  conformed  to  these  standards  of  size.2  It  will  be  seen, 
therefore,  that  the  standardization  which  is  a  benefit,  national  or 
international  in  accordance  with  its  scope,  follows  from  a  well- 
defined  system  of  units,  and  when  such  a  system  is  single  and 

1  See  Presidential   Address  of   R.    M.    Catlin  before    Mechanical    Engineers' 
Association  of  the  Witwatersrand,  abstracted  in  Engineering  and  Mining  Journal 
<New  York),  vol.  Ixxix.  1905. 

2  See  p.  173,  chap.  vii. 


156     EVOLUTION   OF    WEIGHTS   AND   MEASURES 

universal  there  is  bound  to  result  a  single  set  of  standards  in  all 
important  industries.  Such  a  result  is  bound  to  promote  com- 
merce and  industry  by  facilitating  the  manufacture  and  exchange 
of  commodities,  and  the  same  benefits  would  be  experienced  by 
the  world  at  large  as  have  been  realized  in  the  United  States 
where  this  policy  has  been  followed  in  many  lines. 

International  weights  and  measures  soon  would  produce  truly 
international  standards,  both  of  size  and  of  quality,  and  the  trade 
of  the  world  would  be  on  a  far  more  wholesome  and  active  basis, 
as  there  would  not  be  material  tied  up  in  odd  sizes,  and  con- 
sequently unavailable  to  other  users  except  at  increased  expense, 
but  there  would  be  a  common  world  stock.  As  trade  would  be 
stimulated  and  diversified  a  further  division  of  labor  would  take 
place,  and  there  would  be  greater  general  prosperity.  To  become 
thoroughly  convinced  of  this,  one  has  only  to  refer  to  the  reports  of 
American  and  British  consuls,  which  are  unanimous  and  constant 
in  reiterating  the  assertion  that  the  lack  of  an  international 
system  of  weights  and  measures  acts  most  strongly  against  the 
extension  of  trade  between  their  home  countries  in  those  places 
in  which  they  serve.  This,  of  course,  implies  a  reciprocal  loss,  as 
the  wider  the  distribution  of  a  nation's  commerce  the  more 
extensive  it  must  be,  as  also  the  more  profitable. 

That  there  is  need  of  an  international  system  of  weights  and 
measures  which  is  universal  and  invariable  is  shown  by  the  fact 
that  the  United  States  and  Great  Britain,  which  claim  the  same 
sources  for  their  various  weights  and  measures,  now  have  units 
that  figure  constantly  in  trade  relations  which  are  quite  unlike  in 
value.  For  example,  wheat  and  other  grain  from  America  is  sold 
by  a  bushel  which  differs  materially  from  the  British  bushel,  as 
does  also  the  gallon  used  in  the  measurement  of  petroleum,  while 
the  hundredweight  of  112  pounds  and  quarter  of  56  pounds  are 
rarely  used  in  America.  These  weights  were  abandoned  in 
Liverpool  in  1903  for  a  weight  of  50  pounds,  the  use  of  which  in 
trade  was  authorized  by  an  Order  in  Council  of  October  9,  1903. 
Since  that  time  a  standard  for  this  amount  has  been  constructed 
and  verified,  and  there  is  an  increasing  tendency  towards  using 
the  cental  of  100  Ibs.  as  a  commercial  unit.  Here  are  examples 
of  the  inconvenience  where  two  countries  employ  measures  and 
weights  apparently  the  same,  but  which  must  be  adjusted  even  for 


THE    METRIC   SYSTEM   FOR   COMMERCE        157 

transactions  between  themselves,  when  by  the  adoption  and  use  of 
the  metric  system  they  would  be  put  on  the  same  basis  as  regards 
one  another  as  they  would  enjoy  towards  the  rest  of  the  world. 

Foreign  commerce  presents  many  difficulties  unknown  to 
business  between  two  parties  in  more  or  less  proximity.  There 
is  the  question  of  time  and  of  freight,  both  important  items  in 
any  commercial  transaction,  but  especially  so  when  weeks  or 
months  must  elapse  before  a  delivery  can  be  effected.  Misunder- 
standings or  mistakes  are  most  costly  and  cannot  be  rectified 
promptly ;  consequently  there  should  be  the  most  complete 
understanding  between  the  parties  to  the  transaction.  This  must 
involve  an  easy  standard  or  basis  of  comparison,  for  the  present 
differences  in  money  and  exchange  are  troublesome  enough.  The 
extent  of  this  difficulty  is  best  illustrated  by  modern  methods  of 
doing  business  where  catalogues,  price-lists,  and  other  printed 
matter  are  used  so  extensively,  and  are  such  an  important  adjunct 
to  the  work  of  the  salesman,  who  naturally  is  unable  to  carry 
with  him  a  complete  line  of  samples,  even  of  agricultural  tools, 
not  to  mention  dynamos  and  steam  engines.  If  these  descriptions 
and  prices  are  understood,  and  if  the  sellers  have  a  good 
reputation,  much  has  been  done  towards  effecting  a  sale,  as  the 
prospective  buyer  can  tell  at  a  glance  whether  character,  quality, 
and  size  are  such  as  he  desires  and  uses,  and  especially  whether 
they  will  correspond  in  size  with  present  or  future  stock  or  plant. 
Furthermore,  in  case  of  an  immediate  demand  for  the  goods, 
business  can  be  transacted  satisfactorily  by  cable  or  telegraph. 
When,  however,  various  articles  are  presented  to  a  foreign  pur- 
chaser described  in  strange  units,  the  latter  is  compelled  to 
employ  conversion  tables,  and  even  then  fails  at  a  complete,  not 
to  speak  of  quick,  comprehension  of  the  goods.  With  a  single 
system  the  case  would  be  different,  and  no  nation  would  enjoy 
any  advantage  over  another  in  this  respect,  save  in  the  actual 
merit  of  its  goods,  and  the  increased  circulation  and  use  of  such 
catalogues  would  provoke  keener  competition,  and  would  result 
in  a  higher  grade  of  tools  and  other  articles,  as  the  world  markets 
would  be  aimed  at  where  general  excellence  and  price  would 
carry  the  day. 

The  question  whether  a  country's  export  business  would  be 
helped  by  an  international  system  of  weights  and  measures  must 


158     EVOLUTION   OF   WEIGHTS   AND   MEASURES 

be  considered,  no  matter  whether  that  country  is  on  a  protection 
basis  or  enjoys  free  trade.  In  the  latter  case  the  advantages  are 
obvious,  but  where  there  has  been  protection  the  result  in  many 
nations  is  that  the  product  is  often  greater  than  the  needs  of  the 
home  market,  consequently  the  manufacturer,  in  order  to  keep  up 
his  production  on  the  largest,  and  therefore  most  economical 
scale,  must  seek  to  market  his  surplus  in  a  foreign  field.  A 
glance  at  our  table  (page  105)  will  soon  show  that  with  the 
exception  of  Great  Britain  and  its  dependencies,  Eussia,  Denmark, 
and  China,  the  vast  majority  of  nations  are  on  the  metric  basis,, 
and  for  reasons  we  have  already  advanced  it  is  quite  necessary 
that  business  with  them  should  be  done  according  to  the  inter- 
national measures.  That  this  is  essential  is  shown  by  the  fact 
that  in  the  United  States  certain  manufacturers,  and  the  number 
is  constantly  increasing,  not  only  describe  their  goods  in  metric 
measures,  but  so  construct  them,  and  stand  ready  to  increase 
their  business  in  this  respect.  If  the  surplus  product  is  made  so- 
that  it  can  be  utilized  in  any  country,  it  is  of  course  obvious  that 
the  manufacturer  has  a  far  wider  range  of  market,  and  is  likely 
to  secure  better  prices. 

Possibly  the  best  testimony  as  to  the  advantages  to  commerce 
of  an  international  system  of  weights  and  measures  should  come 
from  countries  where  the  metric  system  has  supplanted  the  local 
system  or  systems,  though  the  latter  still  survive.  Such  is  the 
following  extract,  which  sums  up  the  conditions  in  Spain,  and 
which  is  typical  of  the  enlightened  opinion  in  nearly  all  metric 
countries :  "  The  facility  and  security  afforded  to  the  sending  of 
orders,  owing  to  the  amount  ordered  being  subject  to  the  same 
measure  in  the  different  countries,  the  conformity  in  transport, 
custom-house,  and  commission  tariff,  etc.,  attract,  tighten,  increase 
commercial  relations." l  This  is  the  answer  of  the  Spanish 
Geographical  and  Statistical  Institute  attached  to  the  ministry  of 
Public  Instruction,  Agriculture,  Industry,  and  Public  Works,  in 
reply  to  a  question  as  to  how  the  adoption  of  the  metric  system 
had  affected  its  commerce,  and  it  is  also  the  experience  of  other 
countries.  The  importance  of  the  adoption  of  the  metric  system 

1  Report  of  Her  Majesty's  Representatives  in  Europe  on  the  Metric  System,  pre- 
sented July,  1900,  part  i.  p.  61  ;  Parliamentary  Accounts  and  Papers,  1900,. 
vol.  xc. 


THE   METRIC   SYSTEM   FOR   COMMERCE 

to  international  trade  has  been  noted  formally  by  various  com- 
mercial and  statistical  conferences  and  conventions,  but  of  a  more 
official  character  was  the  action  taken  by  the  International 
American  Conference  which  was  held  at  Washington  in  1890, 
where  the  following  resolution  was  adopted :  "  Resolved  that  the 
International  American  Conference  recommends  the  adoption  of 
the  metrical  decimal  system  to  the  nations  here  represented 
which  have  not  already  adopted  it."  James  G.  Elaine,  then 
Secretary  of  State,  whose  last  important  official  work  was  towards 
the  extension  of  American  commerce  through  reciprocity  treaties 
with  the  South  American  countries,  urged  upon  the  United  States 
Government  the  adoption  of  that  system  for  the  customs  service,1 
and  his  recommendations  were  concurred  in  by  Secretary  of  the 
Treasury  Windom  (Report,  Dec.  1,  1890),  and  by  Secretary  of 
State  Foster,  in  his  reports  for  1891  and  1892.  Likewise,  in 
Great  Britain  there  was  a  conference  of  Colonial  Premiers  at 
London  in  1902,  and  a  resolution  was  formally  adopted  favoring 
the  use  of  the  metric  system  for  all  the  British  colonies.  Fol- 
lowing up  the  matter  the  Colonial  Office  then  communicated  with 
the  various  Colonial  governors,  asking  what  action  was  likely  to- 
be  taken  with  regard  to  this  resolution.  Mauritius  and 
Seychelles  already  used  the  system,  but  the  following  colonies 
were  reported  as  favorable  to  its  adoption :  Australia,  New 
Zealand,2  Cape  of  Good  Hope,  Transvaal,  Orange  River  Colony, 
Southern  Rhodesia,  Gambia,  Northern  Nigeria,  Gibraltar,  British 
Guiana,  Trinidad,  Leeward  Islands  and  Windward  Islands. 
Sierra  Leone,  Southern  Nigeria,  Ceylon,  and  the  Falklands 
stipulated  that  they  were  in  favor  of  it  if  adopted  by  the  United 
Kingdom  or  in  the  Empire  generally.  The  Australian  states, 
while  favorably  disposed,  thought  that  the  matter  should  be 
settled  by  the  government  of  the  commonwealth,  while  Jamaica 
and  British  Honduras  required  the  adoption  of  the  system  by  the 
United  States.  Fiji  and  British  New  Guinea  would  have  to- 
follow  Australia,  just  as  the  Straits  Settlements  and  Labuan  were 
dependent  on  India.  The  Bechuanaland  Protectorate  would  be 
compelled  to  be  in  harmony  with  the  rest  of  South  Africa. 
Opposition  to  the  plans  was  evinced  by  St.  Helena,  Cyprus,  Lagos, 

1Sen.  Exec.  Doc.,  No.  181,  51st  Congress,  1st  Session. 
2  Metric  System  adopted  by  New  Zealand  in  1905. 


160     EVOLUTION   OF   WEIGHTS   AND   MEASURES 

Wei-hai-wei,  Barbados,  and  Bahamas,  while  the  Gold  Coast 
Colony  and  the  State  of  Queensland  were  ready  for  the  system, 
but  anticipated  inconvenience  in  its  adoption.  Natal  reported 
that  some  definite  general  plan  was  necessary  before  an  opinion 
could  be  expressed.  Of  the  remaining  colonies  definite  answers 
were  not  given  by  Newfoundland,  Malta,  or  Bermuda,  and  no 
reply  whatsoever  was  received  from  Canada,  though  it  is 
sufficiently  obvious  that  the  latter  country  would  be  compelled  to 
follow  the  example  of  the  United  States. 

It  will  be  seen  from  the  foregoing  that  these  colonies,  widely 
scattered  over  the  world,  were  for  the  most  part  alive  to  the 
-advantages  attending  the  adoption  of  the  metric  system,  as  by  so 
doing  the  great  trade  of  the  British  Empire  would  then  be  put 
on  the  same  terms  as  that  of  the  rest  of  the  world.  This,  of 
course,  leaves  out  of  consideration  the  trade  of  the  United  States 
-and  its  possessions,  which,  if  brought  into  harmony  with  the 
above,  would  greatly  facilitate  in  the  development  and  prosecution 
of  commerce. 

An  additional  consideration  is  that  new  discoveries  of  mineral 
wealth  and  supplies  of  raw  materials  of  one  class  or  other  have 
within  comparatively  few  years  greatly  extended  the  range  of 
commerce,  and  many  nations  once  thought  uncivilized  and  un- 
productive are  becoming  great  consumers  as  well  as  producers, 
requiring  the  most  varied  supplies  and  machinery.  These 
markets  are  destined  to  prove  among  the  most  valuable  of  the 
world,  and  to  pre-empt  them  is  the  task  of  the  highest  wisdom. 
In  South  America  and  in  all  non-British  colonies  we  find  the 
metric  system  used,  though  with  it  are  often  various  native  or 
local  nondescript  units.  It  is  the  opinion  of  the  consuls  to  these 
places — and  they  at  least  must  be  admitted  to  be  competent 
judges — that  the  use  of  the  metric  system  would  greatly  increase 
trade  of  these  countries  with  America  and  Great  Britain. 

Having  pointed  out  that  the  adoption  of  a  single  system  of 
weights  and  measures  throughout  the  world  would  be  most 
advantageous,  and  would  facilitate  commerce,  therefore  benefiting 
each  and  every  nation  to  a  greater  or  less  extent  depending  on 
its  location  and  the  amount  of  its  foreign  trade,  it  is  now 
necessary  to  consider  just  what  advantages  a  country  not  using 
the  metric  system  would  secure  by  its  adoption,  and  what  dis- 


THE   METRIC   SYSTEM   FOR   COMMERCE        161 

advantages,  if  any,  are  likely  to  be  experienced.  These  advantages 
must  be  practical,  especially  in  a  country  like  the  United  States, 
and  must  appeal  to  the  small  shopkeeper  and  farmer,  as  well  as 
to  the  professor  of  physics,  the  merchant,  and  the  statistician. 
Large,  as  the  question  seems,  it  is  possible  to  simplify  it  by 
eliminating  a  certain  number  of  elements.  Thus,  we  know  that 
workers  in  science  in  America,  Great  Britain,  and  Russia  have, 
for  a  long  time,  universally  employed  metric  weights  and  measures 
in  their  daily  work,  and  have  urged  their  adoption  for  general 
use,  confident  of  their  great  utility  and  superiority.  Also,  that 
other  scientific  men,  whose  work  is  of  a  more  practical  nature, 
such  as  electrical  engineers,  who  constantly  use  the  metric 
weights  and  measures  in  their  work,  have  also  urged  their  general 
adoption.  Consequently,  the  change  would  be  a  distinct  advan- 
tage to  workers  in  this  field,  and  there  is  no  opposition  to  the 
step  to  be  anticipated  from  them. 

At  the  other  end  of  the  scale  must  be  considered  the  average 
citizen  who  does  business  on  a  small  scale,  and  who,  with  his 
household,  uses  weights  and  measures  daily.  In  fact,  looking  at 
the  question  as  a  national  one,  this  seems  to  be  the  most 
important  aspect,  and  should  be  most  carefully  considered,  both 
in  the  light  of  the  experience  of  foreign  countries  and  according 
to  local  conditions.  Reflection,  however,  soon  establishes  the 
fact  that  most  of  these  transactions  take  place  where  the  actual 
goods  are  transferred  in  the  presence  of  the  buyer  and  seller,  and 
some  approximate  idea  of  the  measure  desired  is  in  the  mind  of 
both  of  the  parties  to  the  transaction.  Thus  a  man  buying  sugar 
sees  the  amount  he  is  receiving,  and  knows  the  price  paid,  so 
that  with  properly  sealed  weights  there  is  no  opportunity  for 
injustice,  as  the  man  is  free  to  buy  sugar  where  he  will,  and  at 
the  most  favorable  price,  the  latter  being  governed  by  the  law  of 
supply  and  demand  as  modified  by  trade  conditions.  When  his 
wife  mixes  the  sugar  to  make  cake  her  methods  of  measurement 
are  purely  relative,  and  neither  ounces  nor  grams  are  employed, 
but  approximate  measures,  such  as  tea-cups,  which  are  quite 
independent  of  any  laws  of  metrology.  In  fact,  the  question  has 
been  excellently  summed  up  by  one  of  the  most  distinguished 
opponents l  of  the  introduction  of  the  metric  system  into  the 

1  Dr.  Coleman  Sellers,  Gassier' 's  Magazine,  vol.  xvii.  p.  365,  1900. 

L 


162     EVOLUTION   OF  WEIGHTS  AND  MEASURES 

United  States,  as  follows  :  "  To  the  great  bulk  of  mankind  engaged 
in  trade,  in  buying  and  selling,  in  bartering  and  exchanging,  it 
matters  little  what  system  of  weights  and  measures  they  adopt : 
it  matters  little  whether  they  are  obliged  to  use  a  yard-stick  or 
a  meter  rod,  pounds  or  kilograms,  quarts  or  liters.  The  cost  to 
them  is  the  cost  of  the  few  devices  needed  in  weighing  and 
measuring  ;  the  rationale  of  the  system  may  never  enter  into 
their  thoughts."  Thus,  there  is  no  reason  why,  so  far  as  this 
class  of  people  is  concerned,  a  change  should  not  be  made  if  the 
new  system  supplied  is  superior  for  their  purposes.  This  the 
metric  system  is,  on  account  of  its  great  simplicity,  doing  away 
as  it  does  with  all  compound  relations  for  the  single  ratio  of  ten, 
connecting  weight  and  measures  by  the  weight  of  a  volume  of 
water  as  a  unit,  thus  eliminating  all  odd  equivalents  such  as  the 
fact  that  a  cubic  foot  of  water  weighs  62  J  pounds,  and  finally 
doing  away  with  such  anomalies  as  dry  and  liquid  measures  of 
capacity,  avoirdupois,  Troy,  and  apothecaries'  weight,  long  tons 
and  shori  tons,  hundredweight  of  112  pounds,  and  other  weights 
and  measures  equally  arbitrary,  and  not  susceptible  of  being  put 
into  simple  relation  with  other  quantities. 

Indeed,  the  full  complexity  and  absurdity  of  the  present 
"system,"  so  called,  is  hardly  realized  until  we  stop  to  consider 
that  in  the  United  States  copper  is  weighed  by  one  standard, 
silver  by  another,  medicines  by  a  third,  diamonds  and  other 
precious  stones  by  a  fourth,  and  platinum  and  chemicals  by  a 
fifth,  none  of  which  are  interchangeable  with  one  another  except 
by  means  of  fractions.  Nor  is  the  condition  less  striking  in  the 
case  of  the  measures  of  capacity.  One  unit  is  used  for  wine,  and 
bears  the  same  name  as  a  dissimilar  one  used  for  grain,  while 
gas  is  measured  by  still  a  third  unit.  In  fact,  the  condition  as 
regards  the  last-named  groups  of  units  is  summed  up  in  the 
Anti-metric  Argument  of  the  committee  of  the  American  Society 
of  Mechanical  Engineers,  where  it  is  stated  in  a  passage  already 
quoted : l  "  There  is  no  reason  for  the  English  system  retaining 
the  gallon  and  the  bushel,  except  that  they  are  in  such  common 
use."  For  convenience  of  computation  it  would  be  well  if  the 
gallon  were  216  cubic  inches,  or  the  cube  of  6  inches,  and  the 

1See  pp.  145,  146  ante;  Transactions  American  Society  of  Mechanical  Engineers, 
vol.  xxiv.  1902,  No.  972,  "  Anti-Metric  Argument,"  vii.  p.  676. 


THE   METRIC   SYSTEM   FOR   COMMERCE        163 

bushel  1728  cubic  inches,  or  1  cubic  foot.  A  few  lines  later  in 
this  interesting  argument  some  comments  on  the  various  units  of 
weight  are  concluded  by  the  remark,  "  Both  Troy  weight  and 
apothecaries'  weight  might  be  abandoned."  Here,  from  a  source 
unfriendly  to  the  metric  system,  and  opposed  to  any  fundamental 
changes  in  the  weights  and  measures,  is  to  be  found  a  frank 
admission  that  the  measures  of  capacity  are  inconvenient,  and 
could  be  greatly  improved,  and  that  no  reason  other  than  use 
exists  for  retaining  the  Troy  and  apothecaries'  weight.  Accord- 
ingly, they  propose  to  reconstruct  the  measures  of  capacity  into  a 
new  system  which  would  occasion  all  the  inconvenience  attendant 
on  a  transition  from  one  system  to  another,  and  yet  would  not 
yield  the  advantages  of  a  decimal  basis,  and  division,  or  relation 
between  weights  and  measures  of  the  metric  system,  nor  would  it 
have  the  least  international  value. 

Likewise  in  England  a  society  was  formed  in  1904  under  the 
title  of  the  British  Weights  and  Measures  Association,  which 
had  as  it  object  "  the  defence,  standardizing,  and  simplifying 
(italics  ours)  of  British  weights  and  measures,"  and  to  oppose 
the  introduction  of  the  meter  as  a  British  standard.  Further- 
more, this  society  proposed  the  introduction  of  "simplified  and 
scientifically  related  weights  and  measures  based  upon  existing 
British  measures "  (again  italics  ours).  Now,  with  such  an 
admission  that  the  Anglo-Saxon  weights  and  measures  need 
"  simplification  "  and  to  be  "  scientifically  related,"  it  is  proposed 
to  proceed  on  a  new  basis,  and  construct  and  try  a  system 
that  has  not  been  tested  by  actual  use,  as  has  the  metric  system, 
and  which  in  addition  must  be  pushed  against  the  latter,  despite 
the  fact  that  it  will  doubtless  contain  neither  the  decimal  basis 
nor  the  relation  between  measures  of  length  and  weight.  In 
other  words,  there  would  be  experienced  all  the  inconvenience 
which  would  attend  a  change  to  the  metric  system,  and  at  the 
same  time  the  advantages  obtained  would  be  infinitely  small  in 
comparison  with  what  would  follow  a  decision  to  adopt  the 
latter  completely. 

Moreover,  such  a  proposition  is  by  no  means  new,  for  we 
have  seen  how  Sir  John  Kiggs  Miller,  at  the  end  of  the 
eighteenth  century,  advocated  a  decimal  division  of  the  British 
weights  and  measures,  while  on  October  27,  1863,  Sir  John 


164    EVOLUTION  OF  WEIGHTS  AND  MEASURES 

Herschel,  the  eminent  scientist  and  astronomer,  in  an  address 
before  the  Leeds  Astronomical  Society,  advocated  the  readjust- 
ment of  the  British  Imperial  weights  and  measures  on  a  decimal 
basis  according  to  a  plan  that  at  least  appeared  scientific  and 
methodical.  He  proposed  to  take  as  the  standard  of  length  the 
earth's  polar  axis,  which  in  imperial  inches  was  computed  to 
be  500,482,296,  and  as  a  new,  or  as  he  termed  it,  "  geometrical  " 
inch,  employ  the  su^-goo  ooo  Part  of  tnis>  which  would  differ 
by  less  than  a  thousandth  from  the  customary  inch,  and  be 
at  the  same  time  related  to  a  natural  quantity.  The  unit 
of  weight  would  be  a  cubic  foot  of  water,  and  would  be 
approximately  equal  to  1000  ounces  avoirdupois.  Herschel  says  : 
"  Thus  the  change,  which  would  place  our  system  of  linear 
measure  on  a  perfectly  faultless  basis,  would  at  the  same  time 
rescue  our  weights  and  measures  of  capacity  from  their  present 
utter  confusion,  and  secure  that  other  advantage,  second  only 
in  importance  to  the  former,  of  connecting  them  decimally  with 
that  system  on  a  regular,  intelligible,  and  easily  remembered 
principle  ;  and  that  by  an  alteration  practically  inperceptible  in 
both  cases,  and  interfering  with  no  one  of  our  usages  or 
denominations." 

It  might  be  said  in  passing  that  the  length  of  the  polar 
radius,  as  calculated  by  Sir  John  Herschel,  was  no  more 
accurate  or  permanent  than  the  original  determination  of  the 
length  of  the  earth's  quadrant  by  the  founders  of  the  metric 
system,  while  similar,  though  greater,  errors  have  been  found 
in  his  fundamental  unit  of  weight.  It  is  now  conclusively 
recognized  in  metrology  that  no  terrestrial  dimensions  can  be 
relied  upon  to  furnish  an  accurate  standard  of  length.1  Thus 
we  see  that  a  simple  and  albeit  excellent  step  at  reforming 
British  weights  and  measure  did  not  meet  with  any  greater 
favor  than  the  complete  change  to  the  metric  system  advocated 
about  the  same  time,  and  it  is  quite  probable  that  a  like  fate 
would  to-day  befall  any  similar  proposition.  So  that  the 
question  seems  to  be  not  to  reform  weights  and  measures  by 
gradual  and  slight  improvements,  but,  if  any  changes  can  be 
made,  to  adopt  the  best  possible  system,  notwithstanding  the 


Mendenhall,  "The  Metric  System,"  Appleton's  Popular  Science  Monthly, 
October,  1896. 


THE   METRIC   SYSTEM   FOR   COMMERCE        165 

drawback  of  temporary  inconvenience,  and  for  the  sake  of  the 
future  benefits  which  must  unmistakably  follow. 

Perhaps  the  most  important  question  in  connection  with 
the  adoption  of  the  metric  system  is  whether  the  change 
would  occasion  any  temporary  inconvenience  or  expense  to  the 
people  at  large.  In  the  United  States  the  great  majority  of 
the  people  have  been  educated  in  the  public  schools,  in  most 
of  which  since  1880  the  metric  system  has  been  taught  more  or 
less  effectively  as  an  integral  part  of  arithmetic.  Everyone 
is  used  to  the  decimal  system  as  employed  in  the  national 
currency  and  coinage,  and,  furthermore,  it  must  be  granted  that 
a  higher  standard  of  intelligence  and  adaptability  prevails  in 
the  United  States  than  in  Germany  and  other  European 
countries,  where  but  little  inconvenience  was  experienced  and 
practically  no  injury  was  done  at  the  time  of  the  change.  True, 
there  would  be  in  some  cases  the  cost  of  new  scales,  weights, 
and  measures,  but  it  must  be  remembered  that  these  are  under- 
going constant  deterioration,  and  in  constant  use  the  life  of 
scales  and  weights  is  only  about  two  years.  Therefore,  any  such 
expense  would  be  in  actuality  practically  negligible,  and  doubtless 
would  result  in  distributing  over  the  country  weights  and 
measures  of  increased  accuracy.  Indisputably  some  time  would 
be  required  for  the  complete  assimilation  of  metric  measures  and 
weights,  as  we  have  seen  was  the  case  in  Europe,  but  at  the  same 
time  the  advantages  attending  their  use  would  begin,  and  there 
would  be  employed  tables  of  legal  equivalents  which  would  soon 
educate  all  to  the  necessary  proficiency.  Then,  also,  we  would 
see  for  a  few  years  before  and  after  any  legislative  establishment 
of  the  metric  system,  all  books  for  common  use  containing 
formulas,  recipes,  etc.,  printed  with  all  quantities  in  both  English 
and  metric  measures,  so  that  the  transition  from  one  to  the  other 
either  ideally  or  actually  would  be  attended  with  no  inconvenience. 

In  addition  to  the  marked  advantages  in  the  actual  measuring 
and  weighing  of  everyday  life,  due  to  the  simplicity  of  the 
metric  system,  there  would  be  the  great  saving  of  time  in  the 
schools  where  the  complete  metric  system  taught  in  connection 
with  decimals  would  require  but  a  fraction  of  the  time  now  given 
to  compound  numbers.  In  fact  authorities  on  education  have 
estimated  that  at  least  one  year  of  the  child's  school  course  could 


166     EVOLUTION   OF   WEIGHTS   AND   MEASURES 

be  saved  by  the  adoption  of  the  metric  system,  as  after  its 
employment  in  our  practical  everyday  life,  the  Anglo-Saxon 
measures  would  be  of  little  more  use  than  those  of  the  Greeks 
and  Eomans,  and  would  have  scarcely  more  interest  than  the 
old  measures  of  France  have  to-day. 

It  is  not  necessary  here  to  refer  to  the  great  saving  of  time  in 
making  calculations  involving  quantities  of  produce  of  various 
kind,  although  it  is  by  no  means  unimportant,  for  with  the  class 
of  citizens  we  are  now  considering,  while  bookkeeping  usually 
plays  but  a  secondary  part  in  their  life,  yet  it  is  employed,  and 
the  farmer  or  petty  shopkeeper  will  appreciate  the  saving  of 
time  as  much  as  the  clerk  or  accountant  whom  we  will  consider 
later.  /For  the  mechanic  it  is  amply  demonstrated  that  a  change 
in  measurements  makes  but  little  difference  as  foreign  workmen 
educated  to  the  metric  system  are  able  to  work  in  the  Anglo- 
Saxon  system  without  any  difficulty  whatsoever  and  vice  versa, 
ample  testimony  being  forthcoming  on  both  sides  of  this  pro- 
position. 

In  short,  there  are  no  serious  drawbacks  so  far  as  the  average 
man  and  woman  are  concerned  why  America  and  Great  Britain 
should  not  adopt  the  metric  system,  and  when  it  is  recalled,  how 
practically  no  inconvenience  was  experienced  in  Canada  when  the 
change  was  made  from  shillings  and  pence  to  dollars  and  cents, 
or  in  the  early  days  of  the  United  States  when  its  system  of 
currency  was  established  on  lines  quite  new,  it  is  not  reasonable 
to  anticipate  any  embarrassment  or  difficulty. 

We  are  then  brought  face  to  face  with  the  question,  how  will 
the  adoption  of  a  metric  system  affect  the  internal  commerce  of  a 
country  using  the  term  as  referring  to  the  exchange  of  com- 
modities on  a  somewhat  larger  scale  than  we  have  discussed 
above.  While  such  commerce  depends  for  its  prosperity  on  the 
individual  purchaser,  yet  anything  which  facilitates  it  acts  to  the 
latter's  benefit  in  reduction  of  prices  and  promptness  of  delivery 
and  improvement  of  quality.  This  exchange  is  accomplished 
through  an  intricate  system  of  machinery  in  which  credits,  banks, 
transportation,  and  other  factors  all  enter  to  a  large  degree.  Yet, 
with  the  extension  of  commerce  constantly  going  on,  there  has 
been  no  backward  step,  and  in  its  progress  simplicity  and 
accuracy  in  business  transactions  have  been  the  chief  essentials 


THE   METRIC   SYSTEM   FOR  COMMERCE        167 

which  have  been  aimed  at  and  attained.  Thus  the  use  of 
banking  facilities,  and  the  telegraph,  for  the  exchange  of  money 
have  contributed  to  save  time  and  trouble,  which  in  business  are 
definitely  measured  by  money,  while  typewriter,  telephone,  cal- 
culating machines,  and  new  methods  of  bookkeeping  have  played 
their  part  in  releasing  the  mind  of  the  business  man  to  new  and 
original  activities,  and  to  the  extension  of  his  business  along  such 
directions  as  his  experience  tells  him  are  most  profitable.  With 
such  innovations  must  be  considered  the  adoption  of  the  metric 
system,  as  a  step  in  advance,  since  it  will  simplify  all  calculations 
and  bookkeeping  by  the  elimination  of  useless  multiplications 
which  are  involved  in  the  use  of  the  compound  numbers  employed 
in  the  ordinary  weights  and  measures.  One  immediate  result 
would  be  the  ease  in  determining  errors  and  the  decrease  in  their 
number  through  less  multiplication.  Undeniably,  the  simplest 
mathematical  process  for  man  is  decimal  multiplication,  corre- 
sponding as  it  does  to  his  fundamental  notation,  and  this  simplicity 
has  been  established  uncontrovertibly  in  an  experience  of  over  a 
century  with  the  decimal  system  of  American  money,  where  there 
has  been  demonstrated  its  applicability  to  all  pecuniary  trans- 
actions, both  large  and  small,  from  the  actual  handling  of  the 
currency  to  the  booking  of  credits  and  the  computation  of 
discounts,  interest,  etc.,  not  to  mention  the  ease  with  which  such 
mental  calculation  as  the  determination  of  the  price  for  a  quantity 
from  a  price  for  an  individual  article  or  vice  versa  can  be  made. 

Consequently  there  has  resulted  the  widespread  use  of  per- 
centages and  a  decimal  division  wherever  possible.  Thus,  it  is  a 
matter  of  convenience  that  railway  and  other  shares  shall  be 
valued  on  a  percentage  basis,  and  still  more  convenient  that  the 
par  value  should  be  $100*00,  and  this  practice  has  largely  prevailed. 
For  mining  or  other  shares  where  a  smaller  par  value  is  desired, 
it  is  usual  to  employ  $10*00  or  $1*00,  while  bonds  are  con- 
veniently arranged  on  a  basis  of  $1000*00  each.  Likewise  with 
such  commodities  as  sugar  and  cotton,1  where  it  is  necessary 
to  express  intermediate  values  between  even  cents,  it  has  been 
found  desirable  to  give  up  common  fraction  and  use  a  decimal 

1  The  Liverpool  Cotton  Association  since  October  1,  1902,  has  quoted  cotton 
values  in  hundredths  of  a  penny  instead  of  sixty-fourths.  A  similar  practice  is 
observed  in  America. 


168     EVOLUTION   OF   WEIGHTS   AND   MEASURES 

division  to  facilitate  computation  and  bookkeeping.1  These 
changes  have  been  the  result  of  an  evolution  which  has  been 
independent  of  any  theory,  but  which  has  considered  merely  the 
commercial  availability  of  the  method.  For  shop  costs  a  decimal 
hour  is  often  employed,  and  such  clocks  are  used  in  some 
factories. 

An  instance  of  this  in  American  weights  and  measures  is 
found  in  the  tendency  to  eliminate  as  many  units  as  possible,  and 
to  use  larger  numerical  figures,  as  1000s  of  pounds  instead  of 
tons.  Another  example  was  the  introduction  of  the  short  ton  of 
2000  pounds  to  facilitate  calculation,  and  this  unit  soon  came  to 
be  more  extensively  used  than  the  long  ton  of  2240  pounds 
inherited  from  Great  Britain.  No  difficulty  was  experienced  in 
making  the  transition  from  the  long  to  the  short  ton,  in  com- 
mercial usage,  and  there  is  no  reason  why  any  inconvenience 
should  attend  the  change  to  the  metric  ton.  In  fact,  in  one  of 
the  largest  chemical  works  in  the  United  States, — that  of  the 
Solvay  Process  Company, — where  the  metric  system  is  used 
exclusively,  it  is  customary  to  weigh  the  coal  and  other  supplies, 
when  received,  in  metric  units,  despite  the  fact  that  they  are 
bought  and  invoiced  in  ordinary  weights  and  measures.  This 
company  has  found  it  a  distinct  advantage  in  its  internal 
economy  to  make  use  of  the  metric  system,  and  employs  it  in  all 
calculations,  except  for  specifications  of  machinery  and  wood-work 
that  must  be  constructed  outside  of  their  factory  by  people  to 
whom  the  metric  weights  and  measures  are  practically  unknown. 
An  interesting  example  of  the  superiority  of  the  metric  system  for 
purposes  of  accounting  and  bookkeeping  may  be  cited  in  the 
experience  of  the  Brighton  Eailway  in  England,  which  for  a 
number  of  years  has  employed  the  kilogram  as  its  unit  of  weight 
for  all  its  European  business,  and  the  French  decimal  monetary 
system  for  its  accounts.2  It  is  the  opinion  of  the  officials  of  this 
road  that  the  keeping  of  all  accounts  would  be  simplified  by  using 
metric  weights  and  measures.  In  the  foreign  business  it  would 

lThe  Stock  Exchanges,  however,  still  use  common  fractions  and  commissions 
are  usually  in  eighths  and  sixteenths  of  a  per  cent. 

2  See  testimony  of  Charles  A.  de  Pury,  chief  accountant  of  Brighton  Railway  in 
Report  by  Select  Committee  on  Weights  and  Measures  (Metric  System)  Bill 
[H.L.]  1904,  p.  25. 


THE   METRIC   SYSTEM   FOR   COMMERCE        169 

have  been  possible,  of  course,  to  have  changed  the  French  weights 
and  currency  to  English,  but  the  auditors  of  this  corporation 
believed  that  the  metric  system  would  be  the  more  convenient,, 
and  such  it  has  proved  in  practice. 

The  elimination  of  the  middleman  is  one  of  the  tendencies  of 
modern  trade,  and  the  more  direct  relation  of  consumer  with 
producer  requires  that  business  should  be  done  on  the  simplest 
possible  basis  by  the  contracting  parties.  Now  the  middleman 
in  the  past  was  the  one  who  usually  made  the  transformations  of 
weights  and  measures,  buying  by  one  system  and  selling  by 
another.  Inasmuch  as  often  now  he  is  considered  superfluous, 
in  many  transactions  where  the  buyer  and  seller  come  together 
directly,  it  is  essential  that  a  single  system,  which  must  also  be 
the  simplest,  should  be  employed.  Thus  there  is  no  reason  why 
coal  should  be  sold  at  wholesale  by  the  long  ton  and  retailed  by 
the  short  ton  of  2000  pounds,  or  that  the  dealer  in  drugs  and 
chemicals  imported  by  metric  weights  should  dispose  of  them  by 
avoirdupois  or  apothecaries  pounds.  In  fact,  transformations  of 
weights  and  measures,  or  the  use  of  double  systems,  are  and 
always  have  been  a  fruitful  source  of  complaint  and  controversy. 
Indeed,  it  was  well  said  by  a  British  diplomatic  official  in 
speaking  of  conditions  in  Belgium,  "  The  disputes  which  were 
formerly  so  numerous,  and  which  rendered  long  and  complicated 
calculations  necessary,  have  become  few  and  far  between.  In 
short,  the  adoption  of  the  metric  system  has  done  much  to  ensure 
honesty  in  commercial  transactions."  * 

With  the  decimal  system  can  be  used  such  important  labor 
saving  device  as  slide-rules  and  calculating  machines,  the  latter 
in  particular  now  being  a  feature  of  every  well  equipped  office, 
and  resulting  in  increased  accuracy  and  speed  of  operation.  So 
that  the  way  is  in  part  prepared  for  the  introduction  of  the 
metric  system  to  denote  units  of  quantity  on  account  of  its 
decimal  features,  which  would  fit  in  completely  with  modern 
business  computation,  and  America  could  make  the  change  with 
greater  facility  than  Great  Britain,  or  even  than  that  experienced 
by  any  foreign  country,  on  account  of  its  simple  currency  system. 
With  the  advent  of  the  metric  system  would  come  the  release 

1  Report*  from  Her  Majesty's  Representatives  in  Europe  on  the  Metric  System, 
part  i.  p.  8  ;  English  Parliamentary  Accounts  and  Papers,  1900,  vol.  xc. 


170     EVOLUTION   OF  WEIGHTS   AND   MEASURES 

from  the  various  heterogeneous  arrangements  of  tables  of  length, 
surface,  volume,  capacity,  and  mass  in  which  binary,  duodecimal, 
and  other  relations  are  maintained  and  abandoned  in  accordance 
with  no  consistent  theory  or  system,  constantly  requiring  refer- 
ence to  unwieldy  tables  and  tedious  calculation.  Not  only  is 
there  saving  in  the  time  required  to  learn  the  metric  system  over 
all  others  (and  it  is  safe  to  say  that  any  clerk  working  at  a  new 
task  where  quantities  or  dimensions  of  a  substance  were  involved 
would  have  to  brush  up  his  knowledge  of  compound  numbers 
and  tables,  or  proceed  with  extreme  slowness  and  caution),  but  in 
its  application  there  is  a  most  important  gain  of  time.  The 
result  is  that  more  business  can  be  transacted  with  a  smaller 
office  force,  and  that  the  activity  of  clerks  and  computers  can  be 
turned  in  other  directions. 

The  disadvantages  attending  the  introduction  of  the  metric 
system  will  be  entirely  of  a  temporary  character,  and  if  we  may 
take  the  experience  of  Germany  as  a  guide,  will  prove  far  less 
than  is  feared  by  the  timid.  The  time  lost  by  making  trans- 
formation from  the  old  into  the  new  weights  and  measures  will 
in  reality  prove  much  less  than  is  anticipated,  as  such  operations 
doubtless  will  be  performed  with  the  aid  of  tables,  such  as  will 
be  found  in  the  appendix,  which  not  only  the  government  but 
every  industry  doubtless  will  prepare  to  facilitate  such  work, 
while  for  new  calculations  employing  metric  weights  and  measures 
throughout  there  will  be  a  great  saving. 

The  difficulty  of  minds  learning  to  think  in  a  new  system  of 
weights  and  measures  is  not  so  easily  disposed  of,  but  we  have 
seen  how  convenient  and  easily  applied  are  some  of  the  approxi- 
mations, and  we  have  only  for  most  purposes  to  consider  a  yard 
equal  to  ^  of  a  meter,  two  pounds  equal  to  '9  kilogram,  a  liter  a 
quart,  a  long  ton  equivalent  to  a  metric  ton,  etc.  The  relation 
between  volume  and  capacity  should  be  appreciated  greatly  in 
commercial  work,  as  the  capacity  of  a  tank,  reservoir,  bin,  or  car 
in  appropriate  units  can  readily  be  computed  from  its  dimensions, 
and  then,  knowing  the  specific  gravity,  by  simple  multiplication 
the  weight  of  its  contents  can  be  ascertained. 

With  all  the  inconveniences  of  the  Anglo-Saxon  systems  of 
weights  and  measures  we  are  forced  to  consider  a  still  more 
serious  difficulty,  namely  the  growth  of  a  dual  system  due  to  the 


THE   METRIC   SYSTEM   FOR   COMMERCE        171 

increased  use  of  the  metric  system  as  permitted  by  statute.  It 
cannot  be  denied  that  the  metric  system  has  made  great  progress, 
and  that  by  the  close  connection  of  science  with  industry  that  it 
is  destined  to  be  even  more  widely  employed.  Both  systems 
being  legal,  and  the  metric  measures  coming  into  more  wide 
spread  use,  there  would  result  the  perpetual  necessity  of  con- 
verting from  one  to  the  other  in  commercial  transactions,  and 
while  the  nation  was  waiting  for  the  ultimate  survival  of  the 
fittest  system,  or  the  birth  of  an  ideal  scheme,  incalculable 
inconvenience  and  damage  would  ensue,  as  has  been  shown  many 
times  in  the  past  where  a  nation  at  other  times  than  at  a 
transition  period  has  employed  a  double  standard. 


CHAPTER  VII. 

THE  METRIC  SYSTEM  IN  MANUFACTURING  AND 
ENGINEERING. 

THE  application  of  the  metric  system  to  manufacturing  and 
mechanical  and  other  forms  of  constructive  engineering,  where 
there  has  been  long  use  of  units  of  other  systems,  presents  con- 
fessedly the  most  serious  aspect  of  the  question  of  adopting  the 
international  weights  and  measures.  These  branches  of  human 
activity,  it  must  be  remembered,  had  their  beginnings  in  most 
humble  and  commonplace  sources,  such  as  the  village  smith,  the 
local  carpenter,  or  even  the  aboriginal  savage  with  his  primitive 
loom.  In  this  respect  they  differ  from  electrical  and  civil 
engineering,  and  applied  chemistry,  where  the  applications  of 
science  and  discovery  have  resulted  in  vast  industries  and 
important  technical  professions.  From  their  very  inception  these 
latter  have  been  dependent  on  the  work  of  scientific  men,  using 
the  term  broadly,  and  it  has  been  possible  to  use  such  units  and 
measurements  as  they  have  recommended.  That  these  units 
can  be  developed  rationally  and  systematically,  as  well  as  with 
extreme  simplicity  we  can  see  from  the  electrical  units  which 
will  be  discussed  in  a  subsequent  chapter.  But  in  mechanical 
engineering  and  manufacturing  simple  processes  and  methods 
have  gradually  been  developed  by  the  aid  of  scientific  men, 
and  by  applying  their  discoveries  to  every- day  work,  con- 
sequently the  engineers  have  been  forced  to  use  the  units 
and  measures  of  the  people  rather  than  to  develop  and 
rationalize  such  systems  as  would  best  commend  themselves  to 
their  judgment. 


THE   METRIC   SYSTEM   IN   MANUFACTURING     173 

Improved  methods  of  manufacturing,  however,  have  brought 
about  machinery  and  processes  marked  by  simplicity  and 
efficiency,  and  while  the  advantages  that  will  ensue  ultimately 
from  the  adoption  of  international  weights  and  measures  will 
more  than  compensate  for  any  temporary  inconvenience,  never- 
theless, it  must  be  admitted  that  the  transition  will  involve  some 
serious  problems  and  expense.  Inasmuch  as  comparatively  few 
manufacturing  processes,  or  at  least  individual  plants,  remain 
stationary,  but  are  constantly  undergoing  improvements  either  of 
method  or  machinery,  the  possibility  of  adjustment  to  new 
conditions,  such  as  a  new  system  of  weights  and  measures,  is  not 
so  difficult  as  might  at  first  be  imagined.  Oftentimes  changes  of 
styles  or  classes  of  product  are  made  that  are  far  more  funda- 
mental than  any  changes  that  would  be  involved  by  new 
measures,  and  natural  wear  and  tear  to  machinery  require 
constant  renewals  and  substitutions  at  intervals,  and  in  many 
shops  it  is  considered  good  economy  to  strive  for  a  maximum 
output  at  the  expense  of  individual  machines  and  tools.  Further- 
more, conformation  to  standards,  so  necessary  for  successful 
manufacturing,  does  not  involve  the  blind  adherence  to  such 
standards,  however  honored  and  however  universally  observed, 
after  better  standards  have  been  evolved.  That  such  a  change  in 
units  or  standards  can  readily  be  made  we  know  from  numerous 
instances  in  the  past  where  various  gauges,  screw  threads,  screws, 
etc.,  have  been  changed  without  undue  confusion  and  expense./  A 
notable  instance,  inasmuch  as  the  change  was  radical  and  funda- 
mental, was  made  by  the  printers  of  the  United  States  in  1883, 
when  the  nomenclature  of  the  different  sizes  of  type  was  changed, 
and  a  system  of  measuring  by  points  adopted  to  take  the  place  of 
names  in  use  for  years.  In  fact,/the  adoption  of  various  screw 
threads  in  different  countries,  either  in  the  interest  of  standard- 
ization or  to  obtain  a  better  screw,  and  even  their  modification, 
has  worked  no  great  hardship,  and  such  changes  in  car  coupling 
and  other  devices  recommended  from  time  to  time  in  the  United 
States  by  the  Master  Car  Builders'  Association,  involving  as  they 
often  do  marked  departures  from  sizes  or  styles  in  use  by 
different  railroads,  seem  to  be  made  speedily  and  effectively,  and 
without  such  expense  as  would  occasion  objection  from  controlling 
officials. 


174     EVOLUTION   OF   WEIGHTS   AND   MEASURES 

Numerous  instances  where  changes  of  systems  and  standards 
dealing  with  actual  concrete  things  may  be  cited  to  show  how 
readily  changes  in  manufacturing  and  mechanical  engineering 
have  been  brought  about,  proving  that  it  is  not  only  under  ideal 
conditions,  such  as  the  change  from  local  to  standard  time,  or 
in  an  improved  calendar,  that  scientific  reforms  can  be  effected. 
Once  the  people  concerned  are  convinced  of  the  need  of  the 
change  and  the  superiority  of  a  new  system,  history  shows  that 
the  change  can  be  made  effectively  and  expeditiously,  so  that  at 
present  it  remains  for  the  adherents  of  the  metric  system  to 
convince  the  manufacturing  public  by  demonstrating  its  superiority 
for  their  work,  and  to  show  how  it  may  be  adopted  with  the 
smallest  amount  of  inconvenience.  Possibly  this  will  best  be 
understood  by  considering  briefly  the  relation  of  weights  and 
measures  to  manufacturing  and  constructive  engineering.  If  a 
single  piece  of  machinery  or  a  single  fabric  is  to  be  produced, 
it  is  of  little  moment  what  units  of  weight  and  measures  are 
employed  by  the  designer,  and  what  are  used  by  the  maker, 
provided  that  both  can  understand  each  other,  and  provided  that 
time  and  expense  are  subordinate.  That  this  is  true  is  shown  by 
the  ease  with  which  American  and  English  workmen  can  and  do 
work  from  continental  designs  prepared  according  to  the  metric 
measures  and  vice  versa  on  special  orders.  But  when  thousands 
of  the  manufactured  article  are  required,  and  time  and  economy 
must  be  considered,  or  in  other  words,  when  the  commercial 
conditions  of  successful  manufacturing  have  to  be  met,  then  the 
influence  of  weights  and  measures  as  reflected  in  standards, 
processes,  and  in  numerous  more  or  less  direct  ways,  is  felt. 

/We  may  start  with  the  raw  material,  which  may  be  in  bulk  as 
in  the  case  of  ore,  pig  iron,  crude  chemicals,  baled  cotton  or  wool, 
logs,  etc.,  to  cite  but  a  few  examples,  or  we  may  consider  as  raw 
material,  wire,  sheet  metal,  structural  shapes  from  the  rolling  mill, 
yarn,  boards,  and  other  sawed  or  milled  timber,  to  mention  some  of 
the  innumerable  articles  that  enter  into  manufacturing  processes. 
In  the  case  of  the  former  class  we  have  to  consider  the  same 
principles  discussed  in  the  last  chapter,  as  the  purchase  of  the 
materials  would  be  greatly  simplified  by  having  all  invoices  and 
calculations  of  prices  made  in  the  metric  system,  consequently 
there  would  be  a  saving  of  time  to  the  office.  The  actual 


THE   METRIC   SYSTEM   IN   MANUFACTURING     175 

weighing  would  be  the  same  under  any  system,  though  easier 
with  metric  weights,  but  for  the  computations  involved  in  mixing 
or  otherwise  treating  raw  materials  there  would  be  a  great  saving 
effected  by  using  the  metric  system,  as  it  would  avoid  the 
employment  of  different  classes  of  units,  and  would  be  throughout 
on  a  strictly  decimal  basis.  However  in  this  no  particularly 
serious  questions  arise,  but  with  the  other  class  of  raw  materials 
used  in  manufacturing,  experience  has  shown  and  convenience 
enforces  the  demand  that  they  must  be  supplied  of  certain 
dimensions  which  must  be  of  sufficient  variety  to  fill  all  reason- 
able needs,  prepared  according  to  certain  standards,  and  packed  in 
certain  quantities.  The  dimensions  or  weights  are  taken,  of 
course,  in  conventional  units,  and  the  law  of  supply  and  demand, 
modified  by  co-operative  action  and  trade  customs  among  manu- 
facturers, consumers,  and  dealers,  has  resulted  in  the  establishment 
of  certain  standard  sizes  which  not  only  are  regularly  carried  in 
stock,  but  for  which  have  been  calculated  many  tables  dealing 
with  their  weight,  strength,  elasticity,  resistance,  and  other 
characteristics  useful  to  designer  and  maker  alike.  As  a  result 
the  majority  of  articles  used  in  manufacturing  and  construction 
are  made  only  in  standard  sizes,  for  making  which  special 
machinery  has  been  prepared  and  adjusted,  while  articles  of  other 
dimensions  must  be  specially  made  at  considerably  greater 
expense. 

/This  policy  of  making  articles  in  standard  sizes  has  been 
productive  of  the  highest  benefit  to  the  manufacturer,  and 
the  specialization  that  has  been  brought  about  in  American 
works  and  factories  has  contributed  in  no  small  degree  to  the 
position  in  manufacturing  that  the  United  States  now  occupies 
among  the  nations  of  the  world.  •  This  system  of  standardiza- 
tion is  also  advantageous  to  the  consumer,  who  in  turn 
may  be  just  as  important  a  manufacturer,  only  turning  out  a 
more  finished  or  more  complex  article.  Let  us  see  how  the 
metric  system  would  apply  here.  First,  let  us  take  the  purely 
arbitrary  standards  which  have  no  even  dimensions.  For 
example,  flour  is  manufactured  and  usually  sold  196  pounds  net 
to  the  barrel,  yet  there  is  no  particular  reason  for  this  quantity, 
since  flour  sold  in  sacks  for  export,  where  it  may  be  stowed  the 
more  readily  in  a  vessel's  hold,  usually  is  packed  140  pounds  to 


176     EVOLUTION   OF   WEIGHTS   AND   MEASURES 

a  sack.  Now,  if  there  was  any  reason  for  preserving  these 
particular  quantities  they  could  be  used  in  metric  weights  just  as 
readily  as  at  present,  but  appreciate  the  convenience  if  barrels  of 
100  kilograms  and  sacks  of  exactly  half  that  amount  were 
-employed.  True,  the  miller  would  have  to  adjust  his  automatic 
scales  for  weighing  his  flour,  but  the  product  would  be  turned  out 
in  even  quantities,  and  the  weight  of  carload  or  cargo  would  be  told 
at  a  glance  from  the  number  of  barrels  or  sacks.  Every  trans- 
action from  the  time  that  the  flour  left  the  mill  until  it  was  divided 
by  the  retail  grocer  into  10  kilogram  lots  would  be  facilitated. 

Then  let  us  consider  wire  and  sheet  metals  for  which  there 
have  been  a  number  of  gauges.  These,  for  the  most  part,  have 
been  and  are,  not  only  arbitrary  but  irregular  and  inconsistent,  and 
have  stated  the  thickness  in  decimal  fractions  of  inches,  some  of 
which  are  expressed  to  the  fifth  or  sixth  place.  If  these  numbers 
are  to  be  retained  it  is  certainly  just  as  easy  to  express  the 
thicknesses  in  fractions  of  a  millimeter  as  of  an  inch,  and  in  fact 
this  was  officially  done  in  the  Act  of  March  3,  1893,  when  a 
standard  gauge  for  sheet  and  plate  iron  and  steel  was  established 
by  Congress  1  in  which  the  numbers  were  defined  by  equivalent 
values  in  inches  and  millimeters.  Consequently,  under  the 
existing  legal  gauge,  the  adoption  of  the  metric  system  would 
cause  no  difference  whatever  in  the  making  of  sheet  iron  and 
steel,  and  the  customer  would  find  the  same  legal  sizes  under  the 
metric  system  as  before.  While  no  wire  gauge  has  been  legalized, 
yet,  if  any  of  the  standard  gauges  is  to  be  used,  it  is  quite  as 
easy  to  consider  the  metric  as  the  inch  values  since  the  decimal 
fractions  are  no  greater.  The  gauge  system  at  best  is  bad  in  its 
general  aspect  as  it  always  requires  an  act  of  memory,  and  in 
practice  so  inexact  and  unsatisfactory  that  certain  large  consumers 
in  the  United  States,  notably  the  Great  Electric  Companies, 
have  instructed  their  draughting  rooms  and  purchasing  depart- 
ments to  always  specify  by  actual  dimensions  in  thousandths 
of  an  inch  expressed  decimally.  But  so  long  as  gauges  are 
generally  used,  it  is  necessary  to  consider  just  what  they 
signify  and  what  part  they  play  in  mechanical  operations. 
Formed  as  they  are  of  plates  of  sheet  steel  or  other  metal,  with 
holes  or  openings  with  which  to  test  the  various  samples  of 
1C.  221,  Sec.  1,  27  Stat.,  746,  R.S.  3570. 


THE   METRIC   SYSTEM   IN   MANUFACTURING     177 

materials,  they  are  in  practice  often  at  the  outset  very  inexact  in 
their  graduations,  and  in  any  event  they  sooner  or  later  become 
so  by  the  wear  of  constant  use.  As  regards  their  graduation  and 
division  the  various  standard  gauges  differ  widely  from  one 
another,  and  in  individual  cases,  as  has  been  said,  they  are  hardly 
ever  arranged  systematically  or  methodically.  This  can  readily 
be  appreciated  by  examining  the  tables  in  almost  any  standard 
engineer's  reference  or  so-called  pocket  book,  but  a  hint  can  be 
given  by  the  following  list,  which  shows  the  dimensions  in 
decimal  parts  of  an  inch  for  the  same  number  (No.  2)  of  the 
various  gauges  that  are  all  in  use  in  the  United  States. 

Dimensions  of  No.  2  gauge  according  to  different  standards : 

Inch. 

American  or  Brown  &  Sharpe,  -  '25763 

Birmingham  or  Stubs'  Wire,  -  -  '284 

Washburn  &  Moen  M'fg  Co.,  Worcester,  Mass.,  -  '2625 

Imperial  Wire  Gauge,  -  -  '276 

Stubs'  Steel  Wire,  -  '219 

U.S.  Standard  for  Plate,  -  '265625 

Twist  Drill  and  Steel  Wire  Gauge,  -  -  '221 

Screw  Gauge  for  Machine  and  Wood  Screws,  -  '08416 

Thus  it  will  be  seen  that  material  made  according  to  any  of  the 
above  gauges  is  not  suitable  to  be  used  with  that  made  by 
another  gauge,  as  for  example  there  is  no  correspondence  between 
the  gauge  sizes  of  wire  and  the  twist  drill  which  would  make  the 
hole  in  which  the  wire  might  be  inserted,  or  the  size  of  the  wire 
-and  the  wood  or  machine  screw  into  which  it  might  be  made. 
Consequently  the  present  tendency  is  to  abandon  all  arbitrary 
gauges  and  work  to  decimal  parts  of  an  inch  requiring  all 
materials  to  be  furnished  of  such  dimensions,  a  condition  which 
can  be  easily  determined  with  great  exactness  by  a  micrometer 
caliper  of  low  cost.  Now,  the  use  of  decimals  presents  no 
inconvenience  whatsoever  to  the  average  mechanic,  so  that  at  such 
a  transition  period  as  regards  standard  sizes  of  materials,  there  is 
every  reason  for  adopting  the  metric  system  rather  than  waiting 
until  further  standardization  on  an  inch  basis  shall  have  occurred. 
Instead  of  arbitrary  gauge  numbers  millimeters  and  decimal 
fractions  could  be  employed,  and  there  would  be  the  advantage  of 
having  a  larger  number  of  integral  numbers  and  division  by 


178     EVOLUTION   OF   WEIGHTS   AND   MEASURES 

tenths  and  hundredths,  amply  sufficing  for  all  ordinary  mechanical 
work.  The  workmen,  in  their  measurements,  would  employ  the 
same  form  of  micrometer,  the  reading  of  which  would  be  even 
more  simple,  and  much  greater  interchangeability  would  result 
as  soon  as  materials  were  furnished  in  a  smaller  number,  but 
standard  sizes. 

The  tendency  would  be  towards  a  more  exact  arrangement  on 
a  metric  basis.  Such  a  movement  would  be  gradual,  and  there 
would  be  few  occasions  where  any  difficulty  would  be  experienced. 
Metric  wire  gauges  were  introduced  in  France  in  1894,  and  have 
proved  satisfactory,  their  use  increasing  very  rapidly.  In  fact,  in 
much  work  done  with  such  materials,  as  sheet  metal  and  wire,  as 
well  as  with  other  material,  it  is  rarely  necessary  to  look  for  the 
strictest  exactness  in  conforming  to  a  certain  gauge  as  the  purpose 
can  be  satisfied  by  an  approximation,  and  the  customary  method 
of  payment  being  made  on  a  basis  of  weight  prevents  any 
imposition  or  injustice.  As,  however,  new  dies  or  rolls  were 
required,  these  would  be  carefully  adjusted  to  metric  gauge,  and 
the  older  sizes  would  gradually  become  obsolete,  unless  there 
arose  some  special  demand,  while  in  the  case  of  sheet  metal  it 
would  only  be  necessary  to  have  a  new  setting  of  the  rolls.  It  is 
impossible  to  conceive  of  any  injury  being  done  the  manufacturer, 
for  at  the  worst  he  has  only  to  provide  himself  with  a  few  new 
adjuncts  to  his  larger  tools  and  a  limited  number  of  smaller  tools,, 
which  are  constantly  being  replaced. 

Then  take  the  case  of  the  lumber  mill,  where  planks,  boards, 
joists,  etc.,  are  turned  out  on  an  inch  basis.  How  near  do  these 
dimensions  correspond  in  reality  with  the  sizes  they  are  sold  for  ? 
In  fact,  in  many  instances  planed  boards  of  a  certain  dimension 
do  not  gauge  that  dimension  at  all,  but  represent  what  remains 
after  a  board  sawed  approximately  to  that  thickness  has  been 
planed.  The  carpenter  and  the  cabinetmaker  do  not  demand  so- 
high  a  degree  of  precision  from  the  lumber  dealer  that  the  '4  of  a 
millimeter,  between  25  millimeters  and  an  inch  (25*4  mm.)  cannot 
be  disregarded,  and  here  again  it  is  found  that  most  standard 
sizes  of  lumber  can  be  readily  described  in  metric  measures 
without  the  use  of  decimal  fractions,  and  no  new  machinery 
will  be  required  except  as  new  styles  or  sizes  are  demanded. 

In   actual   manufacturing,   after   the   adoption   of   the    metric 


THE   METRIC   SYSTEM   IN   MANUFACTURING     179 

system,  the  first  step  would  be  the  provision  of  facilities  for 
making  various  articles,  such  as  sheet  metal,  paper,  wire,  cloth, 
etc.,  according  to  metric  dimensions.  This  would  be  to  meet  the 
requirements  of  the  government  and  other  consumers,  who 
desired  goods  according  to  metric  specifications.  In  other  words, 
the  same  process  would  be  gone  through  with  as  occurs  when  a 
large  new  or  special  order  is  received.  As  these  orders  would  be 
in  metric  sizes,  and  conformable  approximately  to  those  that 
experience  had  taught  were  most  serviceable  for  the  particular 
use  for  which  they  were  designed,  they  would  gradually  become 
standards,  and  would  supplant  the  older  sizes.  In  many  cases 
where  materials  are  sold  by  weight,  as  paper  and  wire,  the  effect 
of  a  change  of  dimensions  would  have  no  effect  on  the  price, 
while  a  minute  change  sufficient  to  adapt  the  material  to  a 
regular  metric  dimension  would  in  no  way  affect  its  usefulness  to 
the  consumer,  and  should  there  be  a  slight  increase  in  some 
instances  it  would  be  balanced  by  a  slight  decrease  in  others. 
Indeed,  in  many  instances  only  the  trimming  or  finishing  would 
be  involved,  and  here  it  is  probable  that  the  waste  material  would 
just  as  likely  be  less  than  the  amount  produced  in  making  the 
present  sizes  as  it  would  be  greater,  and  at  any  rate  it  could 
doubtless  be  worked  or  utilized  in  some  way,  the  difficulties  can 
hardly  be  called  serious. 

Linear  measures  and  standards  play  a  prominent  part  in  all 
mechanical  operations,  and  here  the  superiority  of  the  metric 
system  and  its  ready  applicability  may  be  shown.  It  has  been 
the  practice  to  measure  by  successively  halving  the  unit,  and  in 
the  case  of  the  inch  this  has  brought  us  down  to  such  fractions  as 
^%  and  -g*£,  which  are  awkward  both  for  computation  and 
observation  on  a  scale.  While  it  is  quite  natural  to  halve  or 
quarter  a  unit,  yet  to  pursue  this  policy  of  binary  subdivision  too 
far  is  extremely  inconvenient.  With  the  metric  system  in  linear 
as  in  other  measurements  it  is  possible  to  make  use  of  any 
decimal  multiple  or  submultiple  of  the  meter  from  the  micron  to 
the  myriameter  as  the  base,  according  to  the  nature  of  the 
measurement  involved,  and  it  is  quite  possible  to  use  the  half  of 
it  simply  by  writing  '5,  or  the  quarter  by  writing  '25,  both 
expressions  requiring  no  more  figures  than  the  corresponding 
common  fractions,  and  involving  no  difficulty  in  case  it  is  desired 


180     EVOLUTION   OF  WEIGHTS   AND   MEASURES 

to  transpose  to  a  higher  or  lower  unit.  Now,  it  has  been  found 
better  in  actual  experience  when  other  fractions  than  a  half  or 
quarter  are  desired,  to  divide  decimally,  and  where  accurate  work 
is  demanded  it  has  become  the  almost  universal  custom  in  the 
United  States  among  engineers  and  machinists  to  work  in 
hundredths  and  thousandths  of  inches,  the  practice  being  followed 
from  draughting  room  to  shop.  This  practice  involves  the  ex- 
pression of  all  quantities  in  terms  of  a  single  unit,  such  as  feet, 
inches,  or  pounds,  with  the  appropriate  decimal  fraction,  and 
demonstrates  the  availability  of  the  decimal  system  for  such 
practical  work,  as  well  as  for  mere  computation.  This  practice  is 
rapidly  on  the  increase,  due  largely  to  the  use  of  calipers  and 
gauges  thus  divided,  so  that  the  matter  of  decimal  fractions 
presents  no  disadvantage,  but  rather  a  convenience,  to  the 
workman  who  has  to  make  measurements. 

As  regards  the  linear  units  themselves ;  if  the  workman 
employs  millimeters  he  has  a  unit  which  is  a  whole  number,  and 
is  superior  to  ^,  as  the  latter  is  too  large,  and  represents  coarse 
measurement  and  work.  On  the  other  hand  ^  is  too  fine  a 
division  for  an  ordinary  scale,  especially  for  a  draughtsman,  and 
is  only  useful  on  a  steel  scale,  with  which  few  mechanics  are 
equipped,  consequently  the  centimeter  and  millimeter  are  quite  as 
convenient  as  the  inch,  while  the  foot,  which  is  rarely  used  in 
modern  mechanical  engineering,  is  in  no  way  missed.  Even  if  we 
consider  the  inch  as  the  principal  unit  we  are  forced  to  use,  either 
its  sixteenth  part,  or  its  tenth,  hundredth,  or  thousandth,  and  in 
reality  we  make  such  a  fractional  part  our  standard  unit,  and  we 
have  the  odd  relation  between  such  units  and  the  greater  ones, 
the  -inch,  and  the  foot,  as  compared  with  the  simple  decimal 
relation  of  the  metric  linear  measures.  The  yard  and  the  meter 
wherever  desired  are  units  of  the  same  class,  and  what  can  be 
done  with  one  is  equally  possible  with  the  other,  not  to  mention, 
of  course,  the  advantage  of  the  decimal  relation  of  the  meter  to 
its  sub-multiples.  But  the  great  gain  is  that  all  calculations  are 
made  in  the  same  unit  as  the  original  measurement,  and  no 
reductions,  save  the  transfer  of  a  decimal  point,  are  ever 
necessary.  Contrast  this  with  the  English  system  where 
measurements  made  in  inches  must  be  changed  to  feet  or  yards 
for  use  with  tables  or  vice  versa. 


THE   METRIC   SYSTEM   IN   MANUFACTURING     181 

i 

But  in  most  manufacturing  there  is  comparatively  little  or  no 
measuring  for  the  workman  to  do,  inasmuch  as  he  is  required 
merely  to  make  his  work  according  to  gauges,  or  templates, 
or  jigs,  which  are  supplied  to  him  by  the  tool  room,  where 
they  have  been  carefully  worked  out  from  the  specifications 
of  the  draughting  room.  /Holes  are  bored  and  reamed  to  a 
certain  gauge,  drills  are  set  so  that  several  will  come  down  on 
the  piece  of  work  at  places  previously  determined  by  the  jig,  and 
planers,  shapers,  milling  machines,  etc.,  are  all  operated  in  the 
same  way.  But  there  must  be  some  consideration  of  standards 
and  units  in  the  draughting  room  and  tool  room,  is  the  suggestion 
immediately  made,  and  here  possibly  would  be  one  of  the  points 
where  difficulty  might  be  encountered.  It  has  been  shown  in 
actual  experience  that  the  work  of  the  draughtsman  in  preparing 
plans  according  to  metric  measures  is  not  only  no  harder,  but  is 
facilitated  considerably  in  actual  drawing,  and  immeasurably  so 
if  there  are  computations  to  be  made.  Now,  in  the  construction 
of  gauges  and  tools  the  highest  intelligence  of  the  mechanical 
force  is  employed,  and  here  there  are  men  not  only  having  a 
knowledge  of  current  sizes  and  standards,  but  perfectly  capable  of 
working  in  any  kind  of  measures.  In  fact,  the  dimensions  of 
many  gauges  are  merely  nominal,  and  there  is  a  greater  or  less 
deviation  from  the  stated  dimensions,  but  which  concern  neither 
draughtsman  nor  workman  if  all  tools  and  gauges  are  harmonized 
as  they  must  be  to  these  dimensions  throughout  the  work.  This, 
of  course,  involves  the  use  of  micrometers  and  other  adjuncts  to 
fine  measuring,  and  this  class  of  work  can  be  done  with  greater 
facility  in  the  metric  system,  as  is  shown  by  its  adoption  by 
makers  of  instruments  of  precision,  opticians,  and  watchmakers 
universally.1  If  tools  and  gauges  in  the  factory  are  to  remain  as 
before  the  introduction  of  the  metric  measures,  as  they  can  be 

1  The  Swiss  watchmakers  were  the  first  to  employ  a  metric  thread  for  small 
screws,  and  the  basis  of  the  system  was  to  start  with  a  pitch  or  distance  between 
threads  of  one  millimeter,  and  to  decrease  the  pitch  of  each  succeeding  size  by 
ten  per  cent.  In  1869  not  only  were  metric  threads  adopted  by  the  American 
Watch  Company  for  watches,  but  also  throughout  their  factory,  and  all  their 
watchmaking  machinery  has  been  constructed  on  that  basis.  In  Great  Britain  a 
Committee  of  the  British  Association  for  the  Advancement  of  Science  appointed 
to  determine  a  gauge  for  small  screws  used  in  telegraph  and  electrical  apparatus 
reported  in  favor  of  the  Swiss  series  of  small  screws,  and  the  same  was  adopted. 


182     EVOLUTION   OF   WEIGHTS   AND   MEASURES 

without  the  slightest  inconvenience,  it  is  only  necessary  to 
designate  them  by  their  metric  values  for  purpose  of  computation, 
and  to  continue  employing  them  with  their  various  shop  numbers 
as  before.  Where  new  standards  and  gauges  are  to  be  con- 
structed, as  they  must  be  from  time  to  time,  then  it  would  prove 
desirable  to  use  the  metric  measures,  and  the  tendency  will  be  to 
work  toward  even  dimensions  and  universal  standards.  Such  a 
tendency  will  be  general,  and  if  the  manufacturer  need  tools, 
which  he  must  buy,  he  will  soon  find  that  the  new  ones  carefully 
standardized  will  be  forthcoming  in  metric  sizes,  wherever  any 
changes  are  made  from  existing  patterns  and  numbers.  To  such 
a  degree  of  exactness  is  this  work  now  carried  on  in  well- 
organized  American  shops,  that  the  highly  skilled  man  in  charge 
of  the  tools  will  find  little  trouble  in  adopting  the  metric 
dimensions. 

Making  the  supposition  now  that  a  machine  shop  or  factory  is 
required  to  work  to  actual  correct  dimensions  in  the  metric 
system,  which,  of  course,  is  not  contemplated  by  any  movement 
for  the  introduction  of  the  new  system,  it  does  not  mean  that  a 
new  equipment  of  tools  must  be  procured.  None  of  the  larger 
tools  would  be  changed,  as  even  in  the  case  of  the  lathes  a  single 
gear  wheel  connected  to  the  lead  screw  enables  metric  threads  to 
be  cut  on  an  ordinary  lathe  with  an  inch  lead  screw  and  vice 
versa,  while  the  'only  important  changes  would  be  such  small 
tools  as  drills,  reamers,  taps,  dies,  etc.,  where  in  certain  dimensions 
a  new  size  might  be  demanded,  and  these,  if  not  already  made 
and  in  stock,  as  are  gear  cutters  for  cutting  metric  pitches l  at 
the  present  time  in  the  United  States  and  England,  would  soon 
be  provided  by  tool  makers. 

In  this  connection  the  cutting  of  screws  may  be  discussed 
more  at  length,  as  it  is  one  of  the  principal  undertakings  in  a 
machine  shop,  and  involves  the  greatest  care  in  order  to  secure 
high  precision  and  interchangeability.  Screw  threads  originally 
are  made  upon  a  lathe  where  a  cutting  tool  is  given  a  lateral 
motion  by  means  of  a  screw  known  as  a  lead  screw  which 
revolves  in  a  nut  attached  to  the  tool  carriage,  and  thus  gives  a 
lateral  motion  to  the  tool.  The  object  on  which  the  screw  is 
being  cut  is  also  revolved,  and  the  proper  ratio  of  revolution 

1  Bevel  gears  can  be  cut  to  metric  pitch  with  the  usual  tools. 


THE   METRIC   SYSTEM   IN   MANUFACTURING     183 

between  the  two  is  maintained  by  suitable  gearing.  In  the 
United  States  and  England  lathes  are  usually  designed  to  work 
on  an  inch  basis,  and  consequently  the  lead  screw  is  so  divided 
and  the  corresponding  gears  furnished.  But,  by  the  use  of  one 
change  wheel  with  127  teeth1  it  is  possible  to  arrange  a  lathe  so 
that  with  a  lead  screw  divided  on  an  inch  basis  metric  threads 
may  be  cut  with  an  error  that  can  only  be  detected  by  the  most 
refined  methods,  if  at  all,  and  such  screws  are  entirely  suitable 
for  all  ordinary  use,  being  correct  to  one  part  in  6350.  By  such 
means  are  made  the  taps  of  hard  steel  with  which  holes  are 
threaded,  and  the  dies  that  are  used  for  the  more  rapid  cutting 
of  threads  on  a  large  scale  in  the  actual  manufacture  of  screws 
in  quantities. 

While  the  adoption  of  the  metric  system  does  not  necessarily 
involve  the  doing  away  with  the  present  systems  of  screw  threads 
in  the  United  States  and  England,  which,  however,  are  purely 
arbitrary,  and  could  be  measured  in  millimeters  with  equal 
facility,  yet  there  is  a  metric  thread  which  was  approved  at  a 
congress  of  engineering  societies  held  at  Zurich  in  October,  1898, 
and  again  at  an  international  conference  held  in  October,  1900,  at 
Paris,  delegates  being  present  from  all  the  important  metric 
nations  of  the  Continent,  including  France,  Germany,  Switzerland, 
and  Italy.  This  form  of  thread  was  evolved  by  the  Socie'te* 
d'Encouragement  pour  1'Industrie  Rationale  of  France,  having  been 
devised  by  M.  Ed.  Sauvage,  and  used  for  a  number  of  years  on 
the  French  railways  previous  to  its  adoption  by  the  society. 
With  slight  modifications  it  was  adopted  as  an  international 
standard  for  shape  of  thread  and  pitch,  and  is  now  known  as  the 
Systerne  International,  abbreviated  to  S.I.  or  S.J.  The  shape  of 
this  thread  is  practically  the  same  as  that  of  the  U.S.  standard 
adopted  by  the  U.S.  Navy  Department  in  1868,  and  also  known 
as  the  Franklin  Institute  or  Sellers  Standard,  from  the  name  of 
its  inventor,  William  Sellers.  The  thread  of  the  bolt  or  screw 
consists  in  cross  section  of  an  equilateral  triangle,  giving  an  angle 
of  60  degrees  as  compared  with  55  degrees  in  the  Whitworth 
(British)  standard,  and  the  edges  and  bottom  of  the  thread  are 
flattened  by  an  amount  equal  to  ^  the  height.  A  modification 
and  improvement  over  the  Sellers  thread,  as  well  as  over  the 

1  This  represents  five  times  the  ratio  of  the  inch  to  the  millimeter. 


184     EVOLUTION   OF   WEIGHTS   AND   MEASURES 

Whitworth  thread,  consists  in  allowing  for  clearance  between  the 
base  of  a  nut  thread  and  the  top  of  a  bolt  thread,  though  in 
American  machine  shop  practice  it  has  been  usual  so  to  make 

Common  Sizes  of  Screw  Threads. 


Diam. 

Whitworth. 
(Inches.) 
Diam. 
Thds.  per  inch.        Increment. 

Diam. 

S.I. 
(mm.) 

Pitch. 

Diam. 
Increment. 

i 

20 

6 

1 

2 

f 

16 

8 

1-25 

8^ 

2 

J 

12 

10 

1-5 

•g 

2 

i 

11 

12 

T75 

4 

| 

10 

16 

2' 

'g 

4 

i 

9                  -L 

20 

2-5 

4 

1 

8 

24 

3- 

•§  ~* 

6 

l* 

i 

30 

3-5 

6 

li 

7 

36 

4' 

6 

11 

6  ;  i 

42 

4'5 

6 

1J 

i 

48 

5 

8 

2 

4.1 

56 

5-5 

^ 

8 

21 

4 

64 

6 

j 

8 

2J 

4 

72 

6'5 

4 

8 

2f 

3J 

80 

7- 

3 

3| 

the  thread  that  there  is  such  a  clearance,  the  sides  of  the  thread 
and  nut  receiving  the  fit.  In  the  S.I.  thread  this  clearance  amounts 
to  ^  of  the  thread  in  the  form  of  a  circular  fillet  tangent  to  the 
thread's  side,  while  the  thread  itself  has  a  flat  top.  The  pitches 


THE   METRIC   SYSTEM   IN   MANUFACTURING     185 

or  distances  between  the  threads  increase  regularly  by  a  half 
millimeter,  with  a  "25  millimeter  interval  in  some  cases,  as 
between  1  and  2  millimeters.  The  rate  of  increase  is  much  more 
regular  and  simpler  than  in  the  case  of  the  United  States 
standard  thread,  where  in  many  places  awkward  fractions  are 
introduced.  The  pitch  of  the  latter  is  finer,  thus  making  a  bolt 
constructed  on  the  Systeme  International  a  trifle  weaker,  but  the 
difference  is  not  serious,  and  no  disastrous  effects  have  been 
experienced  in  actual  use.  The  underlying  symmetry  and  the 
regularity  are,  however,  features  of  great  value,  and  the  system  at 
the  time  of  its  adoption  was  thought  worthy  of  widespread  use, 
even  to  supplant  the  Whitworth  thread,  which  despite  its  English 
basis  has  been  in  wide  use  for  years  even  in  metric  countries.1 

In  watchmaking  the  metric  thread  is  employed  universally,  the 
Swiss  system  being  taken  as  the  standard ;  while  for  small 
machine  screws  used  in  electrical  and  other  apparatus  there  is 
the  B.A.  (British  Association)  standard,  which  is  also  metric. 
The  latter  thread  was  devised  by  a  committee  of  distinguished 
electricians  and  experimental  physicists,  and  since  its  adoption 
the  regularity  and  symmetry  of  its  divisions  have  been  thoroughly 
appreciated. 

//The  change  to  the  Sellers  thread  in  the  United  States  was 
made  without  any  paralysis  of  manufacturing  industries  or 
serious  injury  to  machine  work,  and  the  same  was  true  when  the 
railroads  adopted  a  standard  screw  thread  and  gauge  on  the 
recommendation  of  a  committee  of  the  Master  Car  Builders' 
Association,  which  reported  in  1882.  This  report2  shows  the 
advantages  to  be  gained  by  adopting  and  adhering  to  one  system, 
and  outlines  the  problem  that  was  solved  by  the  late  Professor 
William  A.  Eogers  and  the  Pratt  and  Whitney  Company  in 
preparing  suitable  standards  for  adoption  by  all  railroads.  This 
change  was  made  in  the  course  of  a  few  years  without  undue 
difficulty  or  expense,  and  since  has  been  found  amply  justified, 
illustrating  most  strikingly  the  advantages  of  a  common  standard 
in  a  single  industry. 

1  Henry  Hess,  "The  S.J.  Standard  Metric  Thread  in  Continental  Europe,'* 
American  Machinist,  p.  422,  vol.  xxiii.  No.  18,  May  3,  1900. 

2M.  N.  Forney,  Chairman,  Railroad  Gazette  (New  York),  July  7,  1882,  vol.  xiv. 
p.  407. 


K^* 

V     OF  THE 


186     EVOLUTION   OF   WEIGHTS   AND   MEASURES 

The  adoption  of  the  metric  system,  however,  does  not 
necessarily  involve  the  changing  of  the  present  excellent  screw 
system  of  the  United  States,  as  it  is  perfectly  possible  to  get 
along  with  arbitrary  names  and  gauges  based  on  original 
standards,  and  well  defined  in  terms  of  metric  as  well  as  the  old 
measures.  Just  as  "  tenpenny "  nails  are  now  spoken  of,  so 
screws  could  be  defined  by  number  even  if  they  were  based  on 
obsolete  linear  measures  and  standards.  On  the  other  hand,  if 
the  tendency  should  be  towards  a  new  international  gauge  it  will 
come  gradually,  and  without  undue  inconvenience,  as  similar 
changes  have  been  made  in  the  past. 

In  Great  Britain,  where  possibly  the  standardizing  of  screws 
and  screw  threads  has  not  been  developed  so  highly  as  in  the 
United  States,  the  situation  has  been  most  excellently  summed  up 
by  Alexander  Siemens,  the  well-known  electrical  engineer  and 
manufacturer.  In  his  Presidential  Address *  before  the  (British) 
Institution  of  Electrical  Engineers,  delivered  November  10,  1904, 
he  said : 

"  As  a  last  resort  the  expense  of  changing  the  screw  threads 
is  urged  against  the  change  to  the  Metric  System,  and  the 
Continental  practice  of  calling  their  system  '  Whitworth  thread ' 
is  considered  an  incontrovertible  proof  that  the  metrical  screw 
thread  is  impracticable.  If  all  taps  and  dies  and  leading  screws 
had  to  be  exchanged  at  once,  it  would  certainly  be  a  costly  affair, 
but  such  a  measure  is  not  likely  to  be  adopted,  as  no  advantage 
could  result  from  it.  For  the  real  difficulty  with  screw  threads 
is  that  giving  dimensions  on  paper  is  not  sufficient  to  ensure  that 
the  screws,  manufactured  according  to  such  instructions  in 
different  works,  are  really  interchangeable.  This  subject  has 
been  investigated  by  a  committee  from  the  War  Office,  and  their 
conclusions  throw  a  very  interesting  light  on  the  controversy. 
In  their  opinion  it  is  only  possible  to  obtain  interchangeable 
screws,  if  the  leading  screws  by  which  they  are  made  have  all 
been  cut  on  the  same  screw-cutting  lathe,  or  are  at  least  cut  on 
benches  which  are  fitted  with  a  leading  screw  manufactured  on 
the  same  original  bench.  If  another  link  is  interposed,  differences 
in  the  screws  turned  out  become  perceptible.  As  a  consequence 
of  the  finding  of  the  committee  a  screw-cutting  lathe  has  been  set 

1  Electrician  (London),  Nov.  11,  1904,  p.  149. 


THE   METRIC   SYSTEM   IN   MANUFACTURING     187 

up  at  the  National  Physical  Laboratory,  where  leading  screws 
for  screw-cutting  lathes  are  to  be  manufactured.1  The  same 
experience  has  been  had  in  other  countries,  where  nominally 
*  Whitworth's  threads '  are  used.  It  is  not  possible  to  make 
screws  interchangeable  by  prescribing  their  dimensions,  the  only 
way  is  to  obtain  taps  and  dies  or  leading  spindles  cut  by  the 
same  tools.  If  it  is  a  case  of  extreme  accuracy,  there  is  no 
difficulty  in  cutting  English  thread  by  means  of  a  metric  lathe,  or 
vice  versa" 

To  appreciate  just  what  would  be  the  immediate  effects  of 
the  adoption  of  the  metric  system  in  mechanical  engineering  it 
is  interesting  to  study  the  experience  of  a  large  engine  works 
and  machine  shop  in  England — Messrs.  Willans  and  Robinson,  of 
Rugby — which  enjoys  a  reputation  for  extremely  accurate  work 
together  with  progressive  ideas  associated  with  the  best  engineer- 
ing practice.  This  firm  employs  in  its  works  the  metric  measures 
of  length,  and  not  only  are  they  preferred  by  their  draughtsmen 
and  engineers,  but  also  by  the  workmen  in  the  shops,  who  did 
not  experience  the  slightest  difficulty  in  accustoming  themselves 
to  the  new  system  or  to  employing  it  interchangeably  with  the 
customary  measures.  Inasmuch  as  this  shop  has  been  and  is 
now  experiencing  some  of  the  conditions  attendant  on  a  transition 
period  from  the  customary  to  the  metric  measures  its  experiences 
are  of  interest.  They  employ  bolts  whose  diameter  is  turned  to 
the  nearest  even  millimeter  larger  than  the  size  of  thread  and  on 
them  cut  a  thread  of  the  standard  Whitworth  pattern.  One  of 
their  engineers,  Mr.  Ernest  R.  Briggs,  in  describing  the  use  of  the 
metric  system  in  the  shop's  work  has  written:2  "I  have  seen  new 
machines  built  in  the  metric  system  side  by  side  with  existing 
lines  built  in  the  English  system,  and  I  have  seen  standard 
parts  of  one  set  of  machines  made  to  work  in  with  standard 
parts  of  the  other  set,  and  I  have  also  made  and  sent  into  the 
shops  drawings  in  which  a  single  large  and  complicated  casting 
has  been  figured  in  each  system.  I  can  make  no  defence  for 

1  The  screw  of  this  lathe  is  six  feet  in  length,  and  is  made  of  compressed  steel, 
the  thread  being  cut  with  such  accuracy  that  it  is  said  to  be  correct  to  i0ooo  of 
an  inch  at  60°  Fahrenheit.      The  lathe  is  installed  in  a  constant  temperature 
room  at  Bushy  House.     [Authors.] 

2  Ernest  R.  Briggs,  p.  450,  vol.  xxv.  American  Machinist,  1902 ;  also  a  second 
paper  by  the  same  author  on  p.  1347  of  the  same  volume. 


188     EVOLUTION   OF  WEIGHTS   AND   MEASURES 

this  latter,  but  it  shows  what  can  be  done  in  working  the  two 
systems  side  by  side  during  the  transition  period."  / 

In  England  there  is  at  present  the  beginning  of  a  lack  of 
uniformity,  as  during  recent  years  much  improved  machinery  has 
been  imported  from  the  United  States  and  from  Germany  and 
Switzerland.  The  former  has  screws  cut  to  the  Sellers  thread, 
while  in  the  latter  the  S.I.  system  is  being  widely  and  increas- 
ingly used.  Consequently,  so  long  as  English  engineers  will  go 
into  the  market  for  the  best  machinery  irrespective  of  its  source, 
as  is  now  the  tendency  of  the  best  and  most  progressive  manu- 
facturers, there  is  bound  to  be  an  increasing  lack  of  uniformity  in 
screws  and  screw-threads. 

As  to  the  effect  of  the  introduction  of  the  metric  system  into 
the  manufacture  of  machinery,  we  cannot  do  better  than  conclude 
by  quoting  from  the  remarks  of  Mr.  S.  M.  Vauclain,  the  superin- 
tendent of  the  Baldwin  Locomotive  Works  of  Philadelphia,  Pa. 
Mr.  Vauclain's  testimony  is  not  only  interesting  and  most 
valuable  from  his  high  reputation  as  a  mechanical  engineer,  but 
from  the  position  that  his  company  enjoys  in  the  manufacturing 
world.  Locomotives  from  its  works  have  been  shipped  all  over 
the  world,  while  the  actual  manufacture  has  been  systematized 
and  specialized  to  such  an  extent  that  unrivalled  speed  of  con- 
struction as  well  as  largeness  of  output  has  been  attained.  Mr. 
Vauclain  says  :  V  "  So  far  as  the  metric  system  is  concerned  from 
a  manufacturer  s  standpoint,  it  certainly  should  have  no  terrors. 
Where — in  what  workshop — can  you  find  a  dozen  men  who  will 
measure  the  same  piece  of  work  and  find  the  same  result  with 
the  ordinary  2-foot  rule,  or  such  scales  as  are  ordinarily  provided 
for  their  use  ?  Could  any  manufacturer  in  America  to-day  rely 
upon  the  accuracy  of  the  measurement  of  its  employees  in  its 
products  ?  Instead  of  having  first-class  fits  and  interchange- 
ability  he  would  have  first-class  misfits  and  ruination  of  his 
trade."  Eeferring  to  the  vast  amount  of  fitting  involved  at  the 
Baldwin  Works,  where  there  is  an  output  of  five  locomotives 
daily  and  a  force  of  workmen  aggregating  11,500,  Mr.  Vauclain 
goes  on  to  say,  "...  it  can  readily  be  understood  how  poorly 
these  locomotives  would  be  fitted  together  if  we  relied  upon  each 
and  every  one  of  these  11,500  men  to  do  the  measuring  necessary 

JS.  M.  Vauclain,  p.  414,  vol.  cliii.  Journal  of  Franklin  Institute,  1902. 


THE   METRIC   SYSTEM   IN   MANUFACTURING     189 

to  fit  these  parts  together  with  the  drawings  furnished  by  the 
draughtsmen  in  their  hands."  / 

Discussing  the  actual  relation  of  the  measures  to  the  work  of 
designing  and  construction,  he  says :  "  What  is  the  natural 
proceeding,  then,  in  a  workshop  of  this  kind  ;  you  receive  the 
drawings  from  the  drawing  room ;  they  are  all  made  to,  we  will 
say,  the  English  measure — 12  inches  to  the  foot,  3  feet  to 
the  yard,  or  whatever  you  please — no  matter  how  you  may  see  fit 
to  speak  of  it ;  but  really  and  truly  these  drawings  are  not  made 
to  the  ordinary  English  measure:  they  are  made  to  a  scale  which 
is  adopted,  and  which  represents  12  inches  to  the  foot,  or  3  feet 
to  the  yard,  or  so  many  sixteenths  inches  to  an  inch.  The  scale 
that  we  have  adopted  .in  our  draughting  room  is  a  scale  of 
2  inches  to  the  foot,  and  in  comparing  everything  that  we  look 
at,  we  do  not  consider  the  foot  at  all :  but  if  it  is  2  inches  long  it 
is  a  foot  long." 

"When  a  change  of  this  kind  would  commence  in  any  manu- 
facturing establishment,  it  would  first  commence  in  the  drawing- 
room  (because  unless  the  drawings  were  made  in  accordance  with 
the  metric  system,  the  men  in  the  shop  could  never  work  to  it), 
and  there  would  be  very  few  gauges  in  use  in  the  shop  that 
would  have  to  be  changed,  because  the  gauges  do  not  depend 
upon  the  figured  dimensions  on  the  drawings ;  the  drawings 
would  all  be  figured  for  the  gauges.  A  certain  gauge  would  be 
called  for  instead  of  a  certain  dimension.  In  our  works  to-day 
there  is  not  a  single  hole  drilled  in  a  connecting  rod  where  the 
straps  are  fitted  on  the  stub  ends  of  the  rods,  that  is  drilled  to 
a  dimension  ;  the  drawings  do  not  refer  to  any  dimensions  ;  we 
have  no  use  for  dimensions,  but  we  have  for  gauges.  They  are 
marked  to  be  drilled  with  a  certain  gauge  and  a  certain  bushing 
piece.  You  could  not  use  an  inch  and  a  quarter  drill  in  a  inch 
and  an  eighth  bushing.  Whatever  bushing  you  use  determines 
the  size  of  the  drill  you  are  going  to  use ;  and  whatever  gauge 
you  use  determines  the  distance  apart  the  holes  may  be  and  the 
number  of  them,  and  the  distance  they  are  from  the  end  to  the 
stub.  The  workman  goes  ahead  and  drills  regardless  of  the 
consequences  in  accordance  with  the  gauge  that  is  ordered  on  the 
drawing ;  and  the  result  is  that  these  parts  are  perfectly  inter- 
changeable, and  hundreds  and  thousands  of  these  parts  are 


190     EVOLUTION   OF   WEIGHTS   AND   MEASURES 

duplicated  from  time  to  time  and  shipped  to  almost  every  country 
on  the  face  of  the  earth,  and  that  without  a  single  dimension 
either  metric  or  English  on  the  card — simply  the  gauge  number 
calling  for  that  part.  This  may  be  met  with  the  remark  that 
those  people  who  do  not  do  their  work  with  gauges  would  not 
find  it  so  easy  to  change ;  but  that  is  easily  confronted  by  stating 
that  no  first-class  shop,  or  any  shop,  no  matter  how  small  it 
might  be,  that  desired  to  enter  into  competition  with  the  world 
would  ever  do  its  work  in  any  other  way  and  expect  to  succeed ; 
it  would  die  a  natural  death  sooner  from  the  fact  that  it  failed  to 
use  gauges  or  jigs  for  the  output  of  its  work — even  though  it  had 
only  one  of  a  kind  to  make — much  sooner  than  it  would  if  it 
undertook  to  use  the  metric  system."1 

1  S.  M.  Vauclain,  p.  417,  vol.  cliii.  Journal  of  the,  Franklin  Institute. 


CHAPTER    VIIL 
METEIC  SYSTEM  IN  MEDICINE   AND  PHARMACY. 

IN  no  branches  of  scientific  work  is  there  greater  need  for 
uniformity  of  weights  and  measures  than  in  pharmacy  and 
medicine,  where  the  entire  world  is  drawn  upon  for  drugs  and 
chemicals  for  therapeutic  purposes,  and  where  the  latest  dis- 
coveries of  such  agents,  or  new  methods  of  their  use,  are  immedi- 
ately communicated  to  the  medical  profession  in  every  civilized 
country.  With  uniformity  of  measures  there  would  result  uniformity 
of  treatment,  and  the  ability  to  compare  various  methods  in 
different  cases.  In  fact,  there  is  no  reason  why  the  medical 
profession  should  not  be  able  to  write  and  speak  in  the  same 
language  as  concerns  their  weights  and  measures  throughout  the 
world  just  as  much  as  the  chemist  and  other  workers  in  pure  and 
applied  science;  such  a  condition  would  also  facilitate  the  exchange 
of  scientific  information,  which  in  the  case  of  medical  intelligence 
would  be  of  incalculable  value.  In  addition  to  this  must  be 
considered  the  commercial  advantages  to  the  general  wholesale 
drug  trade,  the  manufacturing  chemist,  and  the  retail  pharmacist, 
due  to  the  fact  that  many  drugs  are  produced  in  metric-using 
countries,  and  are  there  sold  and  exported  according  to  such 
measures.  These  same  drugs,  when  they  reach  English-speaking 
countries,  customarily  are  sold  according  to  avoirdupois  weight, 
and  are  then  compounded  according  to  apothecaries'  weight — a 
system  which  is  a  survival  from  mediaeval  times,  and  which  finds 
few,  if  any,  defenders  on  grounds  other  than  its  customary  usage. 
The  fact,  however,  must  be  considered  that  the  manufacture  and 
distribution  of  pharmaceutical  products  is  a  trade  that  is  self- 


192     EVOLUTION   OF   WEIGHTS   AND   MEASURES 

contained,  as  it  were,  and  we  do  not  find  the  retail  consumption 
of  drugs  and  chemicals  save  for  medicinal  purposes,  where  the 
measurements  are  by  spoonfuls  or  similar  devices,  and  are  usually 
at  the  direction  of  a  physician,  a  matter  of  great  interest  in  the 
daily  life  of  the  public.  In  other  words,  the  buying,  selling,  and 
compounding  of  drugs  and  chemicals  concerns  the  physician  and 
pharmacist  rather  than  the  general  public,  who,  however,  are  the 
ultimate  consumers,  but  whose  wants  are  not  such  as  to  require 
the  use  of  any  particular  system  of  weights  and  measures,  much 
less  to  insist  upon  it.  The  use  of  the  metric  system  among  the 
manufacturers  and  dealers  in  drugs  and  chemicals  has  been 
constantly  on  the  increase,  in  fact  some  of  them  furnish  their 
products  altogether  according  to  metric  units.  On  the  other 
hand,  the  European  chemical  manufacturer  must  provide  special 
containers  for  all  of  his  products  intended  for  the  American 
market.  Therefore,  it  is  a  fact  that  manufacturers  and  dealers  in 
drugs  and  chemicals  are  more  than  willing  to  adopt  metric 
weights  and  measures  exclusively,  if  they  are  not  already  in  use. 
Furthermore,  we  know  that  the  pharmacist  is  convinced  of  the 
availability  of  the  metric  system  inasmuch  as  it  has  been  adopted 
universally  in  continental  Europe  (in  Germany  since  1858),  and 
figures  exclusively  in  the  United  States  Pharmacopoeia,  and  con- 
jointly in  the  British  Pharmacopoeia  of  1898.  This  brings  us  to 
the  medical  profession,  and  here  we  find  that  in  English-speaking 
countries  there  has  been  great  progress  in  the  use  of  metric 
weights  and  measures  in  writing  prescriptions,  but  that  owing  to 
the  conservative  tendencies  of  medical  colleges  it  is  by  no  means 
general,  and  while  the  majority  of  pharmacists  stand  ready  to 
compound  metric  prescriptions,  comparatively  few  American 
practitioners  write  them.  That  there  is  no  difficulty  involved  is 
shown  by  the  ease  with  which  the  system  was  adopted  by  the 
United  States  Marine  Hospital  Service,  the  Medical  Department 
of  the  United  States  Army,  and  the  Medical  Department  of  the 
United  States  Navy,  as  will  be  further  explained  below ;  while  the 
fact  that  it  is  eminently  desirable  is  demonstrated  not  only  from 
the  testimony  of  those  that  have  used  it,  but  from  resolutions 
adopted  at  various  times  by  representative  national  organizations 
of  physicians  and  surgeons.  Despite  the  fact  that  there  has  been 
no  active  campaign  in  behalf  of  the  metric  system  waged  among 


METRIC   SYSTEM   IN   MEDICINE  193 

physicians  there  has  been  great  progress,  and  when  its  advantages 
are  more  thoroughly  realized  it  is  believed  there  will  be  little 
opposition  to  completely  dropping  the  absurd  antiquated  apothe- 
caries' weights.  The  science  of  medicine  to-day  is  closely  con- 
nected with  chemistry,  physiology,  biology,  microscopy,  and  other 
sciences  in  which  measurement  plays  a  most  important  part.  For 
example,  in  all  experimental  medicine  the  doses  given  to  animals 
are  measured  in  metric  measures,  in  pathology  the  dimensions  of 
an  organ  or  any  part  of  it  are  always  stated  in  centimeters  or 
millimeters,  while  the  oculist  employs  metric  measures  in  all  his 
measures  of  focal  length.  In  short,  wherever  medicine  comes 
into  contact  with  natural  or  exact  science  we  find  that  the  metric 
system  is  employed,  and  there  is  no  reason  why  it  should  not  be 
used  universally.  The  only  excuse  advanced  is  that  the  practi- 
tioner has  learned  all  his  doses  on  the  basis  of  the  old  measures, 
and  that  any  change  not  only  might  result  in  inconvenience  but 
in  possible  danger  to  the  patient,  inasmuch  as  a  mistake  that 
might  prove  fatal  could  be  made  in  writing  out  the  quantities. 
This  is  indeed  a  very  weak  objection,  as  the  pharmacist  or  his 
•clerk  is  constantly  on  the  lookout  for  errors  of  this  or  any  other 
kind  in  prescriptions.  Furthermore,  the  more  advanced  physician 
is  constantly  reading  in  medical  journals  of  new  methods  of  treat- 
ment employed  in  Europe,  where  of  course  the  metric  weights 
and  measures  are  altogether  employed,  and  desiring  to  adopt  such 
remedies  in  his  own  practice  he  must  either  employ  the  metric 
measures,  or  translate  them  into  English,  either  operation  requir- 
ing a  knowledge  of  the  metric  system. 

In  pharmacy  there  are  two  different  methods  of  compounding 
prescriptions  according  to  the  metric  system,  which,  while 
fundamentally  different,  in  their  actual  results  do  not  occasion 
any  very  serious  discrepancies.  In  Continental  Europe  and  in 
countries  where  the  metric  system  is  exclusively  used,  it  is  the 
practice  to  measure  all  substances  entering  into  a  prescription, 
whether  solid  or  liquid,  by  weight,  and  this  consequently  is 
known  as  the  gravimetric  method.  That  is,  the  quantities  are 
•denoted  by  grams,  and  in  Germany  no  designation  of  the  unit 
follows  the  number,  grams  being  understood  in  every  case,  as 
no  other  units  are  employed  for  this  purpose.  This,  of  course, 
furnishes  a  very  accurate  method;  but  in  the  United  States  and 

N 


194     EVOLUTION   OF   WEIGHTS   AND   MEASURES 

Great  Britain,  where  the  metric  system  is  used  it  is  customary  to 
employ  what  is  termed  the  volumetric  method,  where  the  fluids 
are  measured  by  volume  or  capacity  measure,  the  quantities 
being  indicated  in  cubic  centimeters.  The  solids,  of  course,  are 
weighed  in  grams,  and  it  is  usual  to  write  after  the  number  the 
abbreviation  gm.  to  distinguish  from  gr.  denoting  grains,  as  used 
in  the  older  system.  Inasmuch  as  the  specific  gravity  of  water 
is  taken  as  unity,  and  one  cubic  centimeter  of  water  at  its 
temperature  of  maximum  density  weighs  one  gram,  it  will  be 
seen  that  for  water  and  other  liquids  of  approximately  the  same 
specific  gravity  there  is  no  difference  between  the  two  methods, 
and  the  majority  of  the  liquids  used  in  compounding  prescrip- 
tions are  so  near  to  water  in  specific  gravity  that  little  trouble 
is  occasioned;  but  there  are  a  few  instances  in  which  this 
difference  is  material,  according  as  the  liquid  is  either  con- 
siderably lighter  or  heavier  than  water.  These  few  should  be 
borne  in  mind  in  comparing  formulae  on  the  gravimetric  system 
with  those  on  the  volumetric.  Of  the  substances  lighter  than 
water  the  most  important  are  ether,  whose  specific  gravity  is  736 
at  0°C.  and  spirits  of  nitrous  ether,  whose  specific  gravity  is  '837. 
Consequently,  speaking  approximately,  four  parts  by  weight  of 
these  liquids  will  occupy  an  equivalent  space  to  five  parts  by 
weight  of  water.  Alcohol  (proof  spirit)  sp.  gr.  0'79  at  20° 
Centigrade  is  another  substance  similar  in  this  respect.  On  the 
other  hand,  dealing  with  liquids  heavier  than  water,  we  find 
that  glycerin  stands  in  such  a  ratio  that  five  parts  by  weight 
of  it  occupy  the  same  space  as  four  parts  of  water,  while  with 
syrup  this  ratio  is  four  to  three,  and  with  chloroform  three 
to  two.  It  is,  of  course,  possible  to  indicate  on  the  prescription 
that  the  quantities  are  to  be  taken  by  weight;  but  except  in 
such  cases  as  above  noted,  or  in  those  of  an  extraordinary 
character,  the  volumetric  method  is  employed,  and  not  only 
corresponds  more  closely  with  the  older  method,  but  also  is- 
much  more  expeditious,  as  the  fluids  may  be  poured  from 
graduated  measuring  glasses  in  much  less  time  than  they  could 
be  weighed. 

The  profession  at  large  was  not  so  quick  to  see  the  advantages 
of  the  metric  system  as  the  medical  departments  of  the  United 
States  Government,  and  the  first  of  these  to  adopt  the  innovation 


METRIC   SYSTEM   IN   MEDICINE  195 

was  the  Marine  Hospital  Service,  where,  in  accordance  with 
Department  Circular  39,  dated  April  27th,  1878,  it  was  ordered 
that  "  The  Medical  Officers  of  the  Marine  Hospital  Service  will 
hereafter,  for  all  official,  medical  and  pharmaceutical  purposes, 
make  use  of  the  Metric  System  of  Weights  and  Measures." 

This  action,  which  was  the  first  Government  order  issued  in 
the  United  States  to  make  the  use  of  the  metric  system  obli- 
gatory for  any  purpose  whatever,1  followed  the  report  made 
to  Surgeon-General  John  M.  Wood  worth,  which  was  prepared 
by  Oscar  Oldberg,  Phar.D.,  then  Chief  Clerk  and  Acting  Medical 
Purveyor,  U.S.  Marine  Hospital  Service,  in  which  he  called 
attention  to  the  advantages  of  the  metric  system,  and  provided 
the  necessary  rules  for  expressing  quantities  in  that  system, 
and  also  described  the  necessary  methods  to  be  followed  in 
writing  metric  prescriptions. 

In  1881  the  Bureau  of  Medicine  and  Surgery  in  the  U.S. 
Navy  adopted  the  system,  as  on  April  15th  of  that  year  there 
was  approved  by  Secretary  William  H.  Hunt  a  small  volume 
entitled,  Instructions  for  Medical  Officers  of  the  United  States  Navy, 
prepared  by  Medical  Director  Philip  S.  Wales,  U.S.N.  On 
page  10,  Article  2,  Section  1,  was  the  official  direction  that  "the 
Metric  System  of  Weights  and  Measures  shall  hereafter  be 
employed  in  the  Medical  Department  of  the  Navy."  Accordingly, 
the  "  Supply  Table "  in  this  volume  was  prepared  on  a  metric 
basis,  and  supplies  have  since  been  issued  in  accordance  with 
this  system. 

In  1894  the  metric  system  was  adopted  by  the  medical 
department  of  the  United  States  Army,  and  was  put  into 
operation  under  the  provisions  of  the  accompanying  order. 

WAR  DEPARTMENT, 

SURGEON  GENERAL'S  OFFICE, 

WASHINGTON,  April  13,  1894. 
CIRCULAR  : 

Upon  the  publication  of  the  new  Supply  Table  and  receipt  of  the  new 
forms,  all  requisitions,  invoices,  receipts,  and  returns  pertaining  to  medical 
supplies  will  be  in  accordance  with  the  metric  system  of  weights  and 
measures. 

After   the  30th  day  of  June,  1894,  the  use   of  this  system  in  writing 

1  See  Oldberg,  Weights,  Measures  and  Specific  Gravity,  Chicago,  1888,  p.  18. 


196     EVOLUTION   OF   WEIGHTS   AND   MEASURES 

official  prescriptions  is  desired ;  on  and  after  the  1st  day  of  January,  1895, 
such  use  is  hereby  ordered. 

Metric  measures,  weights,  and  prescription  blanks  will  soon  be  issued 
to  all  posts  without  requisition. 

Until  medical  supplies  now  in  stock  in  troy  and  avoirdupois  weights 
are  exhausted,  the  following  approximate  values  may  be  considered  as 
equivalent  in  transferring  original  packages  : 

1  ounce  =    30  grammes. 

1  pound  =      £  kilogram. 

1  fluid  ounce  =    30  cubic  centimeters. 

1  pint  =  500  cubic  centimeters. 

1  quart  =      1  liter. 

1  yard  =      1  meter. 

GEO.  M.  STERNBERG, 

Surgeon  General,   U.S.  Army. 
Approved  : 

DANIEL  S.  LAMONT, 

Secretary  of  War. 

This  order  was  promptly  carried  out  on  the  dates  specified, 
and  all  supplies  were  not  only  handled  within  the  department, 
but  were  purchased  from  dealers  according  to  metric  weights  and 
dimensions.  In  addition,  the  army  surgeons  began  writing  their 
prescriptions  on  the  metric  basis  without  protest  or  difficulty, 
and  the  system  was  soon  in  successful  operation,  and  in  1902 
was  pronounced  by  Surgeon-General  Sternberg  as  eminently 
satisfactory,  the  General  testifying  before  the  Committee  on 
Coinage,  Weights  and  Measures,  Congress,  February  15,  1902, 
when  asked  why  he  would  not  go  back  to  the  old  system : 

"  Because  it  (the  metric  system)  is  so  decidedly  superior.  It  is 
working  smoothly,  and  we  have  no  difficulty  whatever — no 
protests  on  the  part  of  the  people  we  deal  with,  from  whom 
we  purchase.  The  wholesale  druggist  must  necessarily  be 
familiar  with  it."  * 

General  Sternberg  also  said  that  the  principal  reason  for 
the  adoption  of  the  system  was  the  greater  simplicity  of  the 
decimal  system,  and  furthermore  it  was  successfully  used  in 
other  countries,  and  was  a  better  system  than  the  one  in  use. 
An  important  test  came  in  the  Spanish- American  War,  when  the 

1  Page  83,  The  Metric  System  of  Weights  and  Measures.    Committee  on  Coinage, 
Weights  and  Measures  (Hearing),  February  15,  1902. 


METRIC   SYSTEM   IN   MEDICINE  197 


medical  department  was  increased  by  a  number  of  volunteer  and 
contract  surgeons ;  but  the  latter  experienced  no  difficulty  in 
conforming  to  the  regulations. 

In  England  the  feeling  of  the  advanced  members  of  the 
medical  profession  has  been  most  favourable  to  the  metric 
system,  and  in  1904  the  General  Medical  Council  adopted 
the  following  resolution  in  reference  to  the  Bill  then  before 
the  House  of  Lords  :  "  That  the  President  (with  the  Chairman 
of  the  Pharmacopoean  Committee)  be  requested  to  inform  the 
Lord  President  of  the  Privy  Council  that  in  the  opinion  of 
the  Council  it  is  desirable  that,  after  a  sufficient  period  to 
be  fixed  by  law,  the  metric  system  of  weights  and  measures 
should  become  the  one  legal  system  for  the  preparation  and 
dispensing  of  drugs  and  medicines ;  that  the  Council  would 
view  with  favour  the  passing  into  law  of  a  Bill  such  as  that 
now  before  Parliament,  entitled  the  '  Weights  and  Measures 
(Metric  System)  Bill ' ;  and  that  in  that  event  the  Council 
would  be  prepared  to  take  all  necessary  steps  to  give  effect 
to  the  law  by  making  the  proper  modifications  in  the  British 
Pharmacopoeia." 

The  correctness  of  the  prescription  when  written  in  metric 
units  is  much  more  likely  to  be  ensured,  as  there  is  no  possi- 
bility of  mistaking  the  various  units,  since  but  two  are  used 
— the  gram  for  solids,  and  the  cubic  centimeter  for  liquids. 
In  a  prescription  written  in  apothecaries'  weights  and  measures, 
on  the  other  hand,  not  only  are  there  numerous  units — as 
pounds,  ounces,  drachms,  scruples,  grains,  minims,  etc. — but 
these  are  denoted  by  alchemistic  characters  which,  at  least  in 
the  case  of  ounces  and  drachms,  are  susceptible  of  confusion. 
Thus,  not  only  is  there  the  danger  of  errors  in  figures  which 
is  common  to  both  methods,  but  in  the  case  of  the  older 
system  there  are  also  the  characters.  Furthermore,  with 
apothecaries'  weights  it  is  customary  to  denote  the  quantities 
by  Eoman  figures  or  letters,  which  are  much  more  readily 
confused  than  the  Arabic  figures  employed  in  metric  prescrip- 
tions. If  the  decimal  line  is  used,  as  in  a  cash  account,  the 
danger  of  a  misplaced  decimal  point,  or  of  an  occasional  dot 
being  taken  as  a  point,  is  obviated.  In  fact,  these  possible 
errors  attributed  to  the  metric  system  have  been  found  by 


198     EVOLUTION    OF  WEIGHTS   AND   MEASURES 

experience  to  be  altogether  imaginary,  for  a  misplaced  decimal 
point  decreases  or  increases  a  dose  ten-fold.  The  dispenser 
would  therefore  detect  the  error  at  a  glance.  Then  there  is 
the  further  advantage  that  it  is  possible  to  send  by  telegraph 
a  metric  prescription  with  far  greater  facility  than  one  where 
the  Eoman  characters  are  employed. 

While  the  gravimetric  method  may  be  the  most  scientific 
and  exact,  yet  it  must  be  remembered  that  the  dose  cannot 
be  administered  to  the  patient  in  the  great  majority  of  cases 
with  anything  like  scientific  accuracy,  and  it  is  usual  to 
employ  various  domestic  glasses  and  spoons,  which  of  course  give 
a  volumetric  measurement.  In  general  certain  rough  equivalents 
amply  suffice,  and  the  following  measurements  are  used  in  the 
United  States  and  France : 

A  tea-spoonful  =  1  fluid  drachm,  =      5  grams  of  water 

A  dessert-spoonful        =  2  fluid  drachms,  =    10      „  „ 

A  table-spoonful  =  J  fluid  ounce,  =    15       „  „ 

A  tumblerful  =  8  fluid  ounces,  =  240       „  „ 

A  wine  glass  (U.S.A.)  =  2     „         „  =60 

A  wine  glass  (French)  =  5     „         „  =150       „  „ 


CHAPTEE    IX. 
JRNATIONAL  ELECTRICAL  UNITS. 

BESIDE  the  units  incident  to  our  every-day  life  which  we 
have  already  discussed,  it  is  possible  to  derive  from  the 
metric  system  in  connection  with  the  ordinary  unit  for  the 
measurement  of  time  employed  throughout  the  civilized  world, 
a  complete  system  of  units  that  will  answer  for  the  measure- 
ment of  any  and  all  physical  quantities.  For  such  a  system 
it  is  necessary  to  have  as  the  bases  certain  fundamental  units, 
and  with  them  we  may  build  up  and  extend  the  system  as 
occasion  demands.  It  has  been  found  that,  starting  with 
units  of  length,  mass,  and  time,  a  satisfactory  system  can  be 
evolved ;  and  though  there  have  been  several  such  systems 
proposed,  yet  the  one  founded  on  the  centimeter  as  the  unit 
of  length,  the  gram  as  the  unit  of  mass,  and  the  second  as 
the  unit  of  time,  has  met  with  the  greatest  favour.  It  has 
for  many  years  been  the  only  one  employed  in  scientific 
work,  and  has  served  as  a  basis  for  other  and  practical 
units  when  such  have  been  required  or  desired.  As  the 
units  mentioned  have  been  adopted  for  most  scientific  work, 
being  as  small  as  were  convenient  to  employ  in  ordinary 
measuring  processes,  it  is  easy  to  see  why  they  were  chosen 
eventually  as  the  basis  of  a  system  of  units  that  should  be 
complete  and  symmetrical.  From  the  names  of  the  funda- 
mental units  this  system  is  known  as  the  C.G.S.  system, 
and  it  is  our  purpose  to  outline  briefly  its  development  in 
order  that  we  may  trace  the  derivation  of  some  of  the  ordi- 
nary electrical  units  now  in  every-day  use,  and  which  are 


200     EVOLUTION   OF   WEIGHTS   AND   MEASURES 

essentially  metric  in  their  origin.  The  first  suggestion  of 
such  a  system  of  units  was  due  to  Carl  Friedrich  Gauss,  who 
in  1832  proposed  a  system  of  so-called  absolute  units,  which 
had  as  its  base  the  fundamental  units  of  length,  mass,  and 
time.  This  system  was  devised  by  Gauss  while  engaged  in 
the  study  of  terrestrial  magnetism,  in  which  the  intensity  of 
the  earth's  magnetism,  as  well  as  the  declination  and  dip, 
was  to  be  measured  at  different  points  in  Europe.  For  this 
purpose  a  German  Magnetic  Union  had  been  organized  by 
Gauss  and  Alexander  Von  Humboldt,  and  was  actively  engaged 
in  magnetic  studies  from  about  1834  to  1842.  Previously  there 
had  been  no  unit  for  the  intensity  of  magnetism,  and  English, 
physicists  had  taken  the  intensity  at  London  as  the  standard. 
Gauss  believed  that  it  would  be  more  scientific,  as  well  a& 
more  practical,  if  a  system  were  devised  which  would  be 
independent  of  season  or  place,  as  well  as  of  instruments  and 
external  conditions.  Accordingly,  as  the  system  which  he 
proposed  in  1832  was  based  merely  on  the  three  fundamental 
units  mentioned,  he  termed  it  the  Absolute  System.  In  this- 
system  it  was  possible  to  derive  all  necessary  units  from  the 
three  selected  as  fundamental ;  thus  a  unit  of  velocity  was 
obtained  by  defining  it  as  such  a  velocity  as  a  body  would 
have  in  travelling  unit  distance  in  unit  time.  Unit  accelera- 
tion was  the  acceleration  that  a  body  would  experience  when 
it  gained  or  lost  unit  velocity  in  unit  time.  Then,  for  the 
unit  of  force,  it  was  only  necessary  to  take  such  a  force  as 
would  impart  unit  velocity  to  unit  mass  in  unit  time — that 
is,  the  unit  acceleration.  Consequently,  when  it  came  to 
defining  a  unit  of  intensity  of  magnetism,  Gauss  took  such  a 
quantity  of  magnetism  as  would  exert  unit  force  on  a  similar 
quantity  at  unit  distance.1  Now,  as  magnetic  force  was  mani- 
fested by  the  attraction  or  repulsion  of  a  magnetic  pole  when 
placed  in  a  magnetic  fluid,  it  would  be  possible  to  measure 
the  force  by  mechanical  methods,  and  for  this  he  deduced 
the  necessary  equations. 

In  this  way,  by  mathematical  processes  which  are  interesting  but 

1  Resultate  aus  den  Beobachtungen  des  Magnetischen  Vereins,  1836-1842;  Soc. 
Oott.  viii.  1832-1837;  Pogg.  Ann.  xxviii.  §§  241,  591  (1833);  Gauss,  Werke>. 
v.  §  79-118. 


INTERNATIONAL   ELECTRICAL   UNITS          201 

need  not  be  discussed  here,  it  was  possible  for  Gauss  to  determine 
the  intensity  of  the  earth's  magnetic  field  at  any  given  point  on 
its  surface.  While  the  process  of  derivation  was  the  same  as  for 
the  modern  C.G.S.  system,  yet  Gauss  employed  as  the  funda- 
mental units  in  his  Absolute  System  the  millimeter  as  the  unit 
of  length,  the  milligram  as  the  unit  of  mass,  and  the  second  as  the 
unit  of  time.  By  similar  reasoning,  it  was  possible  to  define  the 
unit  charge  of  electricity  as  such  a  charge  as  would  act  on  a 
similar  charge  at  unit  distance  with  unit  force.  So  useful  was 
this  idea  of  absolute  measurement  that  it  was  straightway 
adopted  by  Wilhelm  Weber,  (1804-1891)  and  found  application  in 
his  experiments  to  measure  the  intensity  of  an  electric  current,, 
the  intensity  of  electromotive  force  and  of  resistance ;  the  latter 
investigation  being  further  developed  by  Eudolf  Kohlrausch 
(1809-1858)  in  some  most  valuable  investigations.  Weber's  work1 
is  remarkable  not  only  for  the  fact  that  he  applied  absolute 
measurements  in  electricity,  but  for  his  showing  that  electricity 
was  but  a  manifestation  of  mechanical  energy,  and  consequently 
could  be  measured  in  terms  of  length,  mass,  and  time.  There  was, 
however,  an  important  difference,  in  that  it  was  not  possible  to 
measure  directly  quantities  of  electricity,  but  it  was  necessary  to 
make  such  measurements  by  the  effect  on  some  external  object. 
For  example,  when  Weber  came  to  determine  the  intensity  of  an 
electric  current  in  absolute  measurement,  he  found  three  ways 
open  to  him.  The  first  was  to  determine  the  strength  of  current 
by  its  chemical  or  electrolytic  effect.  In  other  words,  a  unit 
current  would  be  that  which  decomposed  a  unit  mass  of  water 
into  its  chemical  elements  in  unit  time.  Secondly,  the  magnetic 
effect  of  the  electric  current  also  served  as  a  basis  for  measuring 
a  current  of  electricity,  and  a  unit  of  intensity  of  current  he 
defined  as  such  a  current  as  would  exert,  upon  a  magnet  pole,  the 
same  force  as  an  infinitely  small  magnet  of  unit  moment,  placed 
at  the  center  of  a  closed  circuit  of  unit  area  around  which  the 
current  should  flow,  and  perpendicular  to  its  plane.  In  other 
words,  he  defined  his  unit  of  current  according  to  the  measure- 
ments which  could  be  made  with  a  tangent  galvanometer,  as  will 
be  described  below.  Then  thirdly,  the  intensity  of  current  could 

1  Rosenberger,  Geschichte  der  Physik,  vol.  iii.  pp.  302,  514-519.     Braunschweig,. 
1890.     Weber,  Pogg.  Ann.  xcix,  p.  11,  1855. 


202     EVOLUTION   OF   WEIGHTS   AND   MEASURES 


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204     EVOLUTION   OF   WEIGHTS   AND   MEASURES 

also  be  measured  by  the  effect  of  two  currents  flowing  along 
parallel  conductors  distant  from  each  other  by  a  unit  length. 

Following  out  these  three  methods,  Weber  made  a  series  of 
absolute  measurements  and  found  that  they  possessed  a  certain 
ratio  to  each  other.  He  also  found  that,  with  the  galvanometer, 
he  was  able  to  measure  the  quantity  of  electricity  with  which  a 
conductor  was  statically  charged,  by  allowing  it  to  be  discharged 
or  flow  to  the  earth  through  the  galvanometer.  Having  thus, 
been  able  to  measure  the  intensity  of  current  in  absolute  units, 
which  (following  the  example  of  Gauss)  were  based  on  the 
millimeter,  milligram,  and  second,  Weber  then  proceeded  to  make 
absolute  measurements  of  electromotive  force.  The  absolute 
unit  of  electromotive  force  he  defined  as  that  induced  by  unit 
magnetic  force  in  a  circular  conductor  of  unit  area,  if  this 
circular  conductor  were  turned  from  a  position  parallel  to  the 
direction  of  the  magnetic  force  into  one  perpendicular  to  it  in  the 
time  of  one  second.1  Inasmuch  as  he  was  able  to  use  the 
magnetic  field  of  the  earth,  whose  intensity  could  be  measured 
accurately,  and  as  by  his  previous  experiments  he  was  able  to 
measure  the  intensity  of  the  current,  using  the  apparatus  known 
as  the  earth  inductor,  he  was  soon  able  to  make  a  direct 
measurement  of  electromotive  force.  The  earth  inductor,  it 
may  be  said  in  passing,  consisted  of  a  large  coil  of  wire  whose 
axis  of  revolution  was  perpendicular  to  the  lines  of  magnetic 
force,  so  that  when  the  coil  was  revolved  a  current  was  induced 
in  it  which  could  be  measured  by  the  galvanometer. 

With  methods  for  the  absolute  measurement  of  current  and 
electromotive  force  already  known  and  defined,  it  only  remained 
to  measure  the  resistance  in  absolute  units,  and  this,  of  course, 
followed  from  Ohm's  law,  which  had  been  known  since  1827. 
According  to  this  statement,  the  current  was  equal  to  the  electro- 
motive force  divided  by  the  resistance,  and  consequently  it  followed 
that  a  unit  of  resistance  would  be  that  through  which  unit 
electromotive  force  would  produce  unit  current.  This  determina- 
tion of  the  unit  of  resistance  involved  most  elaborate  experiments, 

1  Rosenberger,  vol.  iii.  p.  517;  "  Electrodynamische  Massbestimmungen  ins 
besondere  Widertandsmessen, "  Abhandl.  der  K.  S.  Gesellsch.  I.  §  197,  1852;  Pogg. 
Ann.  Ixxxii.  §  337.  Weber,  Abhandl.  bei  Begriindung  der  K.  S.  Gesellschaft  der 
Wissenschaft,  1846  ;  Abhandl.  der  K.  S.  Gesellschaft  d.  Wissenschaft,  I.  1852. 


INTERNATIONAL   ELECTRICAL   UNITS          205 

which  are  among  the  most  celebrated  in  all  experimental  physics, 
and  their  result  was  firmly  to  establish  the  absolute  system  on  a 
thoroughly  scientific  basis. 

There  were,  previous  to  this,  various  arbitrary  electrical  units 
suggested,  and  in  more  or  less  limited  use.1  Thus  various 
lengths  of  copper,  iron,  or  German  silver  wire  of  specified  length, 
weight,  and  cross-section  were  suggested  and  employed  as  units. 
Perhaps  the  most  conspicuous  of  these  was  the  copper  wire  of 
prescribed  dimensions  and  weight  which  was  recommended  by 
Jacobi,2  of  St.  Petersburg,  in  1846,  to  the  physicists  of  Europe  as 
the  standard  of  normal  resistance.  This  standard  was  determined 
in  absolute  units  of  resistance  by  Weber,  but  it  did  not  prove 
entirely  acceptable,  owing  to  the  changes  taking  place  in  the 
copper  with  time,  and  owing  to  the  difficulties  experienced  in 
obtaining  standard  conditions.  Accordingly,  Werner  Siemens,  of 
Berlin,  proposed,  in  1860,  following  the  suggestion  of  Marie- 
Davy  made  in  1843,  to  use  mercury  in  defining  the  unit  of  resist- 
ance, and  as  a  standard,  a  column  of  this  substance  one  meter  in 
length  and  one  square  millimeter  in  cross-section,  measured  at 
0°C.3  This  also  was  measured  by  Weber  in  1861,  and  later 
by  Kohlrausch. 

For  electromotive  force,  it  was  customary  at  this  time  to 
•employ  the  electromotive  force  of  a  constant  battery,  such  as  the 
Daniell  cell,  and  in  the  case  of  a  current,  to  make  use  of  various 
arbitrary  units.  With  the  increase  in  the  scientific  knowledge  of 
•electricity,  as  well  as  in  its  industrial  applications,  such  as  the 
telegraph  and  submarine  cable,  it  was  realized  that,  for  practical 
use,  there  should  be  a  systematic  and  comprehensive  system  of 
electrical  units,  which  would  be  based  on  certain  fixed  standards, 
and  would  be  universally  employed  by  electricians.  This  subject 
was  accordingly  taken  up  in  Great  Britain  by  the  British 
Association  for  the  Advancement  of  Science,  and  in  1861  a  strong 
committee,  composed  of  leading  physicists  and  electricians,  was 
appointed  to  investigate  the  subject  and  to  report  on  suitable 
units.  The  subject  was  discussed  in  all  its  many  bearings  by 

1  For  a  list  with  bibliography,  see  Rosenberger,  Geschichte  der  Physik,  vol.  iii. 
pp.  519-520. 

2  Jacobi,  Comptes  Rendus  (Paris),  p.  277,  vol.  xxxiii. 
3W.  Siemens,  Poggendorff's  Annalen,  ex.  p.  1,  1860. 


206     EVOLUTION   OF   WEIGHTS   AND   MEASURES 

this  committee,  Weber's  and  other  experiments  were  repeated,  and 
the  result  was  that  an  absolute  system  was  adopted,  only  the 
centimeter,  gram,  and  second  were  employed  as  the  fundamental 
units  in  place  of  the  millimeter,  milligram,  and  second  of  Gauss 
and  Weber.  This  committee  not  only  reported  in  favor  of  the 
establishment  of  the  C.G.S.  system,  but  also  fixed  a  certain 
number  of  so-called  practical  units,  which,  with  slight  modifica- 
tions, are  now  in  universal  use. 

The  reason  for  this  was  that  a  number  of  the  C.G.S.  absolute 
units  are  either  too  large  or  too  small  to  be  employed  in  practical 
work.  For  example,  the  electromotive  force  of  an  ordinary 
Daniell  cell  would  represent  about  108  absolute  units,  and  as  the 
electrician  of  that  time  dealt  with  electromotive  forces  of  this 
magnitude,  rather  than  with  those  represented  by  a  quantity  so- 
much  smaller,  it  was  convenient  to  multiply  the  absolute  unit  by 
108  to  obtain  a  convenient  practical  unit,  which  was  designated 
by  the  name  volt.  Likewise  with  the  ohm,  or  practical  unit  of 
resistance,  which  represented  109  absolute  units.  But  in  the  case 
of  the  ampere,  or  unit  of  current,  which,  as  we  have  seen,  must 
follow  from  Ohm's  law,  the  difference  was  not  so  large,  and  the 
absolute  unit  had  merely  to  be  divided  by  10  to  give  the  practical 
unit.  This  Commission  decided  on  the  coulomb  as  the  unit  of 
quantity,  being  10 -1  absolute  units,  and  being  the  quantity  of 
electricity  conveyed  by  one  ampere  in  one  second.  As  a  unit  of 
capacity,  the  farad,  or  10  ~9  absolute  units,  was  taken,  and  measured 
the  capacity  of  a  condenser  charged  to  a  potential  of  one  volt  by 
one  coulomb.  As  a  more  useful  unit  still,  the  micro-farad,  or  10 ~6 
part  of  a  farad,  was  also  established.  For  work,  the  joule  was 
taken,  representing  107  ergs  or  absolute  units  of  work,  and 
equivalent  to  the  energy  expended  in  one  second  by  one  ampere 
flowing  through  a  resistance  of  one  ohm.  As  a  unit  of  power, 
the  watt,  or  107  ergs  per  second,  represented  the  power  of  a 
current  of  one  ampere  flowing  under  a  pressure  of  one  volt,  or 
one  joule  per  second,  and  when  multiplied  by  1000  it  gives  the 
kilowatt,  which  soon  became  common  in  electrical  work  in  place 
of  the  old  familiar  horse-power.1 

1  For  an  interesting  historical  presentation  which  includes  the  text  of  recent 
legislation,  see  Wolff,  "The  So-called  International  Electrical  Units,"  a  paper 
presented  at  the  International  Congresses  of  Electricians  at  St.  Louis,  1904. 


INTERNATIONAL   ELECTRICAL   UNITS          207 

In  1865  this  committee  made  a  determination  of  the  ohm,  and 
constructed  a  standard  of  platinum-silver  to  represent  its  value. 
This  standard,  by  law,  represented  the  legal  unit  of  resistance  in 
Great  Britain,  and  was  also  known  for  many  years  as  the  B.A. 
(British  Association)  unit ;  in  fact,  holding  its  own,  especially  in 
English-speaking  countries,  until  the  adoption  of  the  international 
ohm  by  the  Chicago  Congress  of  1893. 

Soon  after  this,  the  invention  by  Latirner  Clark,  in  1873,  of  a 
constant  cell,  which  was  found  to  have,  under  certain  conditions, 
an  electromotive  force  of  1'434  volts,  furnished  a  standard  of 
electromotive  force  which,  while  not  legally  defined  until  some 
years  later,  became  widely  used,  and  figured  in  many  determina- 
tions. 

So  thoroughly  was  the  C.G.S.  system  thought  out  by  the 
British  Association  Committee,  and  so  systematically  were  the 
practical  units  determined  and  defined  that,  despite  minor  in- 
accuracies, as  shown  by  the  experiments  of  German  physicists,  the 
system  was  favorably  considered  at  the  International  Congress  of 
Electricians  held  in  Paris  in  1881,  and  resolutions  were  adopted 
in  which  the  C.G.S.  electro- magnetic  units  were  chosen  as  the 
fundamental  units  in  terms  of  which  the  practical  units  should  be 
defined.  At  a  meeting  held  in  1884  an  international  commis- 
sion decided  on  the  length  of  the  column  of  mercury  for  the 
standard  ohm,  and  the  legal  ohm  was  defined  as  the  resistance  of 
a  column  of  mercury  of  one  square  millimeter  section,  and  of  106 
centimeters  length  at  a  temperature  of  melting  ice. 

The  ampere  was  defined  as  a  current  corresponding  to  10 -1 
absolute  C.G.S.  electro-magnetic  units,  while  the  volt  was  defined 
as  an  electromotive  force  which  produced  a  current  of  one 
ampere  in  a  conductor  whose  resistance  was  a  legal  ohm.  This 
definition  of  the  ohm  did  not  carry  with  it  universal  acceptance, 
and  the  legal  ohm  was  not  made  legal  in  Great  Britain  or  in  the 
United  States ;  but  in  the  meantime  a  number  of  prominent 
physicists,  including  Professor  Henry  A.  Eowland  in  America  and 
Lord  Eayleigh  in  England,  carried  on  further  investigations  to 
evaluate  the  true  ohm,  with  the  result  that  the  length  of  the 
mercury  column  was  found  to  be  nearly  106'3  centimeters,  which 

Reprinted  in  Bulletin  No.  1,  Bureau  of  Standards,  Washington,  D.C.     See  British 
Association  Reports  on  Electrical  Standards  (London,  1873). 


208     EVOLUTION   OF   WEIGHTS   AND   MEASURES 

accordingly  was  adopted  by  the  British  Association  Committee  in 
1892,  together  with  the  definition  of  the  column  in  length  and 
mass,  rather  than  by  length  and  cross-section. 

Meanwhile,  in  1889,  another  international  congress  of  elec- 
tricians was  held  at  Paris,  at  which,  in  addition  to  a  number  of 
decisions  involving  nomenclature,  definitions  of  units  of  energy, 
power,  and  inductance  were  adopted.  The  joule  was  selected  as 
the  practical  unit  of  energy  and  was  defined  as  equal  to  107  C.G.S. 
units,  being  equivalent  to  the  energy  disengaged  as  heat  in  one 
second  by  a  current  of  one  ampere  flowing  through  a  resistance 
of  one  ohm.  As  a  practical  unit  of  power  the  watt  was  taken, 
and  was  equal  to  107  C.G.S.  units,  being  the  power  of  one  jouje 
per  second.  For  inductance  the  quadrant  was  chosen  as  the 
practical  unit,  and  was  defined  as  equal  to  109  centimeters.  This 
-congress  also  took  the  important  step  of  recommending  that  the 
power  of  various  electric  machines,  such  as  dynamos,  motors, 
transformers,  etc.,  should  be  rated  in  watts  and  kilowatts  instead 
of  horse-power,  and  this  practice  has  generally  prevailed  even  in 
non-metric  countries  such  as  Great  Britain  and  America. 

In  1893,  in  connection  with  the  World's  Columbian  Exposition 
at  Chicago,  an  International  Congress  of  Electricians  was  held, 
and  a  Chamber  of  Delegates,  composed  of  officials  appointed  by 
the  various  Governments,  proceeded  to  define  and  name  the 
various  electrical  units.  By  this  time,  owing  to  the  increased  use 
of  electric  lighting,  various  forms  of  power  transmission,  electric 
railways,  and  other  important  applications  of  electricity,  the 
subject  was  one  of  prime  interest,  and  required  the  most  careful 
consideration  of  the  Chamber  of  Delegates,  which  consisted  of 
many  of  the  world's  most  eminent  physicists  and  electrical 
engineers.  Its  deliberations  resulted  in  a  series  of  recom- 
mendations which  were  reported  to  the  Congress,  and  referred  to 
the  various  nations  of  the  world,  by  many  of  whom  they  were 
subsequently  embodied  to  a  greater  or  less  extent  in  legal 
enactments  making  the  use  of  the  new  units  obligatory.  In  the 
United  States  such  an  Act  was  passed  and  approved,  July  12, 1894.1 
These  resolutions  contained  the  following  recommendations : 

"Resolved, — That  the  several  Governments  represented  by  the 
delegates  of  this  International  Congress  of  Electricians  be,  and 

1  Revised  Statutes  of  the  United  States,  Supplement,  vol.  ii.  chap.  131,  1894. 


INTERNATIONAL   ELECTRICAL   UNITS          209 

they  are  hereby,  recommended  to  formally  adopt  as  legal  units  of 
electrical  measure  the  following:  As  a  unit  of  resistance,  the 
international  ohm,  which  is  based  upon  the  ohm,  equal  to  109 
units  of  resistance  of  the  Centimeter-Gramme-Second  System  of 
electro-magnetic  units,  and  is  represented  by  the  resistance  offered 
to  an  unvarying  electric  current  by  a  column  of  mercury  at  the 
temperature  of  melting  ice  14*4521  grammes  in  mass,  of  a  constant 
cross-sectional  area,  and  of  the  length  of  106'3  centimeters. 

"  As  a  unit  of  current,  the  international  ampere,  which  is  one- 
tenth  of  the  unit  of  current  of  the  C.G.S.  system  of  electro- 
magnetic units,  and  which  is  represented  sufficiently  well  for 
practical  use  by  the  unvarying  current  which,  when  passed 
through  a  solution  of  nitrate  of  silver  in  water,  and  in  accordance 
with  accompanying  specifications  deposits  silver  at  the  rate  of 
0*001118  of  a  gram  per  second. 

"  As  a  unit  of  electromotive  force,  the  international  volt,  which 
is  the  electromotive  force  that,  steadily  applied  to  a  conductor 
whose  resistance  is  one  international  ohm,  will  produce  a  current 
of  one  international  ampere,  and  which  is  represented  sufficiently 
well  for  practical  use  by  Y^§£  of  the  electromotive  force  between 
the  poles  or  electrodes  of  the  voltaic  cell  known  as  Clark's  cell, 
at  a  temperature  of  15°  C.,  and  prepared  in  the  manner  described 
in  the  accompanying  specification.1 

"  As  a  unit  of  quantity,  the  international  coulomb,  which  is  the 
quantity  of  electricity  transferred  by  a  current  of  one  international 
ampere  in  one  second. 

"  As  a  unit  of  capacity,  the  international  farad,  which  is  the 
capacity  of  a  condenser  charged  to  a  potential  of  one  international 
volt  by  one  international  coulomb  of  electricity. 

"  As  a  unit  of  work,  the  joule,  which  is  equal  to  107  units  of 
work  in  the  C.G.S.  system,  and  which  is  represented  sufficiently 
well  for  practical  use  by  the  energy  expended  in  one  second  by 
an  international  ampere  in  an  international  ohm. 

"  As  a  unit  of  power,  the  watt,  which  is  equal  to  107  units  of  power 
in  the  C.G.S.  system,  and  which  is  represented  sufficiently  well  for 
practical  use  by  work  done  at  the  rate  of  one  joule  per  second. 

1  No  report  was  ever  made  by  the  committee  to  which  the  preparation  of  the 
specifications  was  entrusted.  Its  members  were  Professors  Helmholtz,  Ayrton, 
and  Carhart,  but  the  death  of  the  first  prevented  the  work. 

O 


210    EVOLUTION   OF   WEIGHTS   AND   MEASURES 

"  As  a  unit  of  induction,  the  henry,  which  is  the  induction  in  a 
circuit  when  the  electromotive  force  induced  in  this  circuit  is 
one  international  volt,  while  the  inducing  current  varies  at  the 
rate  of  one  ampere  per  second." 


Specifications  for  Construction  and  Use  of  the  Silver  Voltameter. 

In  the  following  specifications  the  term  silver  voltameter 
means  the  arrangement  of  apparatus  by  means  of  which  an 
electric  current  is  passed  through  a  solution  of  nitrate  of  silver  in 
water.  The  silver  voltameter  measures  the  total  electrical 
quantity  which  has  passed  during  the  time  of  the  experiment, 
and  by  noting  this  time  the  time  average  of  the  current,  or  if  the 
current  has  been  kept  constant,  the  current  itself,  can  be  deduced. 

In  employing  the  silver  voltameter  to  measure  currents  of 
about  one  ampere  the  following  arrangements  should  be  adopted : 

The  kathode  on  which  the  silver  is  to  be  deposited  should  take 
the  form  of  a  platinum  bowl  not  less  than  10  cms.  in  diameter 
and  from  4  to  5  cms.  in  depth. 

The  anode  should  be  a  plate  of  pure  silver  some  30  sq.  cms.  in 
area  and  2  or  3  mms.  in  thickness. 

This  is  supported  horizontally  in  the  liquid  near  the  top  of  the 
solution  by  a  platinum  wire  passed  through  holes  in  the  plate  at 
opposite  corners.  To  prevent  the  disintegrated  silver  which  is 
formed  on  the  anode  from  falling  on  to  the  kathode,  the  anode 
should  be  wrapped  round  with  pure  filter  paper,  secured  at  the 
back  with  sealing  wax. 

The  liquid  should  consist  of  a  neutral  solution  of  pure  silver 
nitrate,  containing  about  15  parts  by  weight  of  the  nitrate  to  85 
parts  of  water. 

The  resistance  of  the  voltameter  changes  somewhat  as  the 
current  passes.  To  prevent  these  changes  having  too  great  an 
effect  on  the  current,  some  resistance  besides  that  of  the  volta- 
meter should  be  inserted  in  the  circuit.  The  total  metallic 
resistance  of  the  circuit  should  not  be  less  than  10  ohms. 

In  the  United  States  the  foregoing  recommendations  were 
duly  given  force  of  law  by  an  Act  of  Congress  approved 
July  12,  1894,  one  section  of  which  provided  that  the  National 


INTERNATIONAL  ELECTRICAL   UNITS          211 

Academy  of  Sciences  should  prepare  detailed  specifications  for 
the  practical  application  of  the  definitions  of  the  ampere  and 
volt.  Such  specifications  were  accordingly  prepared  by  a  com- 
mittee 1  of  the  Academy,  and  were  adopted  by  that  body  on 
February  9,  1895.  They  are  given  in  full  below. 


REPORT. 

In  the  preparation  of  this  report,  in  order  to  have  the  specifications  accord 
with  international  usage,  free  use  has  been  made  of  the  English  Govern- 
ment specifications  and  of  certain  papers  prepared  by  Dr.  K.  Kahle  of 
Germany,  and  Prof.  H.  S.  Carhart  of  this  country. 

SPECIFICATIONS  FOR  THE  PRACTICAL  APPLICATION  OF  THE 
DEFINITIONS  OF  THE  AMPERE  AND  VOLT. 

SPECIFICATION  A. — The  Ampere. 

In  employing  the  silver  voltameter  to  measure  currents  of  about  1  ampere, 
the  following  arrangements  shall  be  adopted : 

The  kathode  on  which  the  silver  is  to  be  deposited  shall  take  the  form  of 
a  platinum  bowl  not  less  than  10  centimeters  in  diameter,  and  from  4  to  5 
centimeters  in  depth. 

The  anode  shall  be  a  disk  or  plate  of  pure  silver  some  30  square  centi- 
meters in  area  and  2  or  3  millimeters  in  thickness. 

This  shall  be  supported  horizontally  in  the  liquid  near  the  top  of  the 
solution  by  a  silver  rod  riveted  through  its  center.  To  prevent  the  dis- 
integrated silver  which  is  formed  on  the  anode  from  falling  upon  the 
kathode,  the  anode  shall  be  wrapped  around  with  pure  filter  paper,  secured 
at  the  back  by  suitable  folding. 

The  liquid  shall  consist  of  a  neutral  solution  of  pure  silver  nitrate,  con- 
taining about  15  parts  by  weight  of  the  nitrate  to  85  parts  of  water. 

The  resistance  of  the  voltameter  changes  somewhat  as  the  current  passes. 
To  prevent  these  changes  having  too  great  an  effect  on  the  current,  some 
resistance  besides  that  of  the  voltameter  should  be  inserted  in  the  circuit. 
The  total  metallic  resistance  of  the  circuit  should  not  be  less  than  10  ohms. 

Method  of  making  a  measurement. — The  platinum  bowl  is  to  be  washed 
consecutively  with  nitric  acid,  distilled  water,  and  absolute  alcohol ;  it 
is  then  to  be  dried  at  160°  C.,  and  left  to  cool  in  a  desiccator.  When 
thoroughly  cool  it  is  to  be  weighed  carefully. 

It  is  to  be  nearly  filled  with  the  solution  and  connected  to  the  rest  of  the 
circuit  by  being  placed  on  a  clean  insulated  copper  support  to  which  a 
binding  screw  is  attached. 

1  Henry  A.  Rowland,  Chairman ;  Henry  L.  Abbot,  George  F.  Barker,  Charles 
S.  Hastings,  Albert  A.  Michelson,  John  Trowbridge,  Carl  Barus. 


212    EVOLUTION   OF  WEIGHTS   AND   MEASURES 

The  anode  is  then  to  be  immersed  in  the  solution  so  as  to  be  well  covered 
by  it  and  supported  in  that  position  ;  the  connections  to  the  rest  of  the 
circuit  are  then  to  be  made. 

Contact  is  to  be  made  at  the  key,  noting  the  time.  The  current  is  to 
be  allowed  to  pass  for  not  less  than  half  an  hour,  and  the  time  of  breaking 
contact  observed. 

The  solution  is  now  to  be  removed  from  the  bowl  and  the  deposit  washed 
with  distilled  water  and  left  to  soak  for  at  least  six  hours.  It  is  then 
to  be  rinsed  successively  with  distilled  water  and  absolute  alcohol  and 
dried  in  a  hot-air  bath  at  a  temperature  of  about  160°  C.  After  cooling 
in  a  desiccator  it  is  to  be  weighed  again.  The  gain  in  mass  gives  the  silver 
deposited. 

To  find  the  time  average  of  the  current  in  amperes,  this  mass,  expressed 
in  grams,  must  be  divided  by  the  number  of  seconds  during  which  the 
current  has  passed  and  by  O'OOlllS. 

In  determining  the  constant  of  an  instrument  by  this  method,  the  current 
should  be  kept  as  nearly  uniform  as  possible,  and  the  readings  of  the 
instrument  observed  at  frequent  intervals  of  time.  These  observations 
give  a  curve  from  which  the  reading  corresponding  to  the  mean  current 
(time-average  of  the  current)  can  be  found.  The  current,  as  calculated  from 
the  voltameter  results,  corresponds  to  this  reading. 

The  current  used  in  this  experiment  must  be  obtained  from  a  battery, 
and  not  from  a  dynamo,  especially  when  the  instrument  to  be  calibrated  is 
an  electrodynamometer. 

SPECIFICATION  B. — The  Volt. 

Definition  and  properties  of  the  cell. — The  cell  has  for  its  positive  electrode, 
mercury,  and  for  its  negative  electrode,  amalgamated  zinc ;  the  electrolyte 
consists  of  a  saturated  solution  of  zinc  sulphate  and  mercurous  sulphate. 
The  electromotive  force  is  1*434  volts  at  15°  C.,  and  between  10°  C.  and  25°  C., 
by  the  increase  of  1°  C.  in  temperature,  the  electromotive  force  decreases  by 
0-00115  of  a  volt. 

1.  Preparation  of  the  mercury. — To  secure  purity,  it  should  be  first  treated 
with  acid  in  the  usual  manner  and  subsequently  distilled  in  vacuo. 

2.  Preparation  of  the  zinc  amalgam. — The  zinc  designated  in  commerce 
as  "commercially  pure"  can  be  used  without  further  preparation.     For  the 
preparation   of  the  amalgam,  1  part  by  weight  of  zinc  is  to  be  added  to 
9  parts  by  weight  of  mercury,  and  both  are  to  be  heated  in  a  porcelain  dish 
at  100°  C.,  with  moderate  stirring  until  the  zinc  has  been  fully  dissolved  in 
the  mercury. 

3.  Preparation  of  the  mercurous  sulphate. — Take  mercurous  sulphate,  pur- 
chased as  pure  ;  mix  with  it  a  small  quantity  of  pure  mercury,  and  wash  the 
whole  thoroughly  with  cold  distilled  water  by  agitation  in  a  bottle ;  drain 
off  the  water  and  repeat  the  process  at  least  twice.     After  the  last  washing, 


INTERNATIONAL   ELECTRICAL   UNITS          213 

drain   off  as   much   of  the   water   as   possible.      (For    further    details    of 
purification,  see  Note  A.) 

4.  Preparation  of  the  zinc  sulphate  solution. — Prepare  a  neutral  saturated 
solution  of  pure  recrystallized  zinc  sulphate,  free  from  iron,   by  mixing 
distilled  water  with  nearly  twice  its  weight  of  crystals  of  pure  zinc  sulphate 
and  adding  zinc  oxide  in  the  proportion  of  about  2  per  cent,  by  weight  of  the 
zinc  sulphate   crystals   to   neutralize  any  free  acid.     The  crystals  should 
be  dissolved  with  the  aid  of  gentle  heat,  but   the  temperature  to  which 
the  solution  is  raised  must  not  exceed  30°  C.     Mercurous  sulphate,  treated 
as  described  in  3,  shall  be  added  in  the  proportion  of  about  12  per  cent, 
by  weight  of  the  zinc  sulphate  crystals  to  neutralize  the  free  zinc  oxide 
remaining,-  and  then  the  solution   filtered,  while  still  warm,  into  a  stock 
bottle.     Crystals  should  form  as  it  cools. 

5.  Preparation  of  the  mercurous  sulphate  and  zinc  sulphate  paste. — For 
making   the  paste,  2  or  3  parts  by  weight  of  mercurous  sulphate  are   to 
be  added   to  1  by  weight  of   mercury.     If   the  sulphate  be  dry,  it  is  to 
be   mixed  with  a   paste  consisting   of  zinc  sulphate  crystals  and  a  con- 
centrated zinc  sulphate  solution,  so  that  the  whole  constitutes  a  stiff  mass, 
which   is   permeated   throughout  by  zinc  sulphate   crystals  and  globules 
of  mercury.     If  the  sulphate,  however,  be  moist,  only  zinc  sulphate  crystals 
are  to  be  added  ;  care  must,  however,  be  taken  that  these  occur  in  excess 
and  are  not  dissolved  after  continued  standing.     The  mercury  must,  in 
this  case  also,  permeate  the  paste  in   little  globules.     It  is  advantageous 
to  crush  the  zinc  sulphate  crystals  before  using,  since  the  paste  can  then  be 
better  manipulated. 

To  set  up  the  cell. — The  containing  glass  vessel,  .  .  .  shall  consist  of 
two  limbs  closed  at  the  bottom  and  joined  above  to  a  common  neck  fitted 
with  a  ground-glass  stopper.  The  diameter  of  the  limbs  should  be  at 
least  2  centimeters  and  their  length  at  least  3  centimeters.  The  neck 
should  be  not  less  than  1*5  centimeters  in  diameter.  At  the  bottom  of 
each  limb  a  platinum  wire  of  about  0'4  millimeter  diameter  is  sealed 
through  the  glass. 

To  set  up  the  cell,  place  in  one  limb  pure  mercury  and  in  the  other 
hot  liquid  amalgam,  containing  90  parts  mercury  and  10  parts  zinc.  The 
platinum  wires  at  the  bottom  must  be  completely  covered  by  the  mercury 
and  the  amalgam  respectively.  On  the  mercury  place  a  layer  1  centimeter 
thick  of  the  zinc  and  mercurous  sulphate  paste  described  in  5.  Both  this 
paste  and  the  zinc  amalgam  must  then  be  covered  with  a  layer  of  the 
neutral  zinc  sulphate  crystals  1  centimeter  thick.  The  whole  vessel  must 
then  be  filled  with  the  saturated  zinc  sulphate  solution,  and  the  stopper 
inserted  so  that  it  shall  just  touch  it,  leaving,  however,  a  small  bubble 
to  guard  against  breakage  when  the  temperature  rises. 

Before  finally  inserting  the  glass  stopper  it  is  to  be  brushed  around 
its  upper  edge  with  a  strong  alcoholic  solution  of  shellac  and  pressed  firmly 
in  place.  (For  details  of  filling  the  cell,  see  Note  B.) 


214    EVOLUTION   OF  WEIGHTS   AND   MEASURES 


NOTES  TO  THE   SPECIFICATIONS. 

(A)  The  mercurous  sulphate.— The  treatment  of  the  mercurous  sulphate 
has  for  its  object  the  removal  of  any  mercuric   sulphate  which  is  often 
present  as  an  impurity. 

Mercuric  sulphate  decomposes  in  the  presence  of  water  into  an  acid  and 
a  basic  sulphate.  The  latter  is  a  yellow  substance — turpeth  mineral — 
practically  insoluble  in  water ;  its  presence,  at  any  rate  in  moderate 
quantities,  has  no  effect  on  the  cell.  If,  however,  it  be  formed,  the  acid 
sulphate  is  also  formed.  This  is  soluble  in  water,  and  the  acid  produced 
affects  the  electromotive  force.  The  object  of  the  washings  is  to  dissolve 
and  remove  this  acid  sulphate,  and  for  this  purpose  the  three  washings 
described  in  the  specification  will  suffice  in  nearly  all  cases.  If,  however, 
much  of  the  turpeth  mineral  be  formed,  it  shows  that  there  is  a  great 
deal  of  the  acid  sulphate  present,  and  it  will  then  be  wiser  to  obtain  a 
fresh  sample  of  mercurous  sulphate,  rather  than  to  try  by  repeated  washings 
to  get  rid  of  all  the  acid. 

The  free  mercury  helps  in  the  process  of  removing  the  acid,  for  the 
acid  mercuric  sulphate  attacks  it,  forming  mercurous  sulphate. 

Pure  mercurous  sulphate,  when  quite  free  from  acid,  shows  on  repeated 
washing  a  faint  yellow  tinge,  which  is  due  to  the  formation  of  a  basic 
mercurous  salt  distinct  from  the  turpeth  mineral,  or  basic  mercuric  sulphate. 
The  appearance  of  this  primrose-yellow  tint  may  be  taken  as  an  indication 
that  all  the  acid  has  been  removed ;  the  washing  may  with  advantage 
be  continued  until  this  tint  appears. 

(B)  Filling  the  cell. — After   thoroughly   cleaning   and  drying  the  glass 
vessel,  place  it  in  a  hot-water  bath.     Then  pass  through  the  neck  of  the 
vessel  a  thin  glass  tube  reaching  to  the  bottom,  to  serve  for  the  introduction 
of  the  amalgam.     This  tube  should  be  as  large  as  the  glass   vessel   will 
admit.     It  serves  to  protect  the  upper  part  of  the  cell  from  being  soiled 
with  the  amalgam.     To  fill  in  the  amalgam,  a  clean  dropping  tube  about 
10  centimeters  long,  drawn  out  to  a  fine  point,  should  be  used.     Its  lower 
end  is  brought  under  the  surface  of  the  amalgam,  heated  in  a  porcelain 
dish,  and  some  of  the  amalgam  is  drawn  into  the  tube  by  means  of  the 
rubber  bulb.      The  point  is  then  quickly  cleaned  of  dross  with  filter  paper, 
and  is  passed  through  the  wider  tube  to  the  bottom  and  emptied  by  pressing 
the  bulb.     The  point  of  the  tube  must  be  so  fine  that  the  amalgam  will 
come  out  only  on  squeezing  the  bulb.     This  process  is  repeated  until  the 
limb  contains  the    desired   quantity   of    amalgam.      The    vessel    is    then 
removed  from  the  water  bath.     After  cooling,  the  amalgam  must  adhere 
to  the  glass,  and  must  show  a  clean  surface  with  a  metallic  luster. 

For  insertion  of  the  mercury,  a  dropping  tube  with  a  long  stem  will 
be  found  convenient.  The  paste  may  be  poured  in  through  a  wide  tube 
reaching  nearly  down  to  the  mercury  and  having  a  funnel-shaped  top. 
If  the  paste  does  not  move  down  freely  it  may  be  pushed  down  with  a 


INTERNATIONAL   ELECTRICAL   UNITS          215 

small  glass  rod.  The  paste  and  the  amalgam  are  then  both  covered  with 
the  zinc  sulphate  crystals  before  the  concentrated  zinc  sulphate  solution 
is  poured  in.  This  should  be  added  through  a  small  funnel,  so  as  to 
leave  the  neck  of  the  vessel  clean  and  dry. 

For  convenience  and  security  in  handling,  the  cell  may  be  mounted  in 
a  suitable  case,  so  as  to  be  at  all  times  open  to  inspection. 

In  using  the  cell,  sudden  variations  of  temperature  should,  as  far  as 
possible,  be  avoided,  since  the  changes  in  electromotive  force  lag  behind 
those  of  temperature. 

Somewhat  similar  specifications  were  prepared  by  the  Board  of 
Trade  of  Great  Britain  and  were  promulgated  in  an  Order 
in  Council,  August  23,  1894.  The  chief  points  of  difference 
besides  phraseology  were  in  the  specifications  for  the  Clark  cell, 
but  these  were  in  no  way  radical.  Canada  also  adopted  regula- 
tions essentially  in  harmony  with  the  above,  as  did  France, 
Austria,  and  Belgium ;  while  in  Germany  the  measure  of  current 
was  made  of  prime  importance,  and  the  specifications  for  the 
silver  voltameter  and  the  method  of  measurement  are  somewhat 
modified.1 

At  the  Paris  International  Electrical  Congress  of  1900  it  was 
decided  to  give  the  name  of  Gauss  to  the  C.G.S.  unit  of  magnetic 
field  intensity,  or  to  such  a  field  as  would  be  produced  by  the 
unit  of  magnetism  at  the  distance  of  one  centimeter,  or,  in  other 
words,  such  a  field  as  would  act  on  a  unit  pole  with  the  force  of 
one  dyne.  Likewise  the  same  congress  gave  sanction  to  the 
name  of  Maxwell  to  denote  the  C.G.S.  unit  of  magnetic  flux  or 
the  number  of  magnetic  lines  within  a  tube  of  force.  The 
magnetic  flux  would  consequently  be  equal  to  the  product  of  the 
intensity  of  the  field  by  the  area,  and  the  unit  would  be  a  single 
magnetic  line.  Thus  magnetic  flux  would  correspond  to  current, 
being  dependent  on  the  magnetomotive  force  and  the  magnetic 
reluctance.  This  step  was  taken  as  these  C.G.S.  units  were 
employed  in  actual  practice  and  apparatus  was  in  common  use 
by  means  of  which  field  intensities  could  be  measured  directly. 
The  name  kilogauss  is  also  employed  to  denote  a  thousand  times 
the  unit.  Other  propositions  have  been  made  for  names  for  the 
C.G.S.  magnetic  units,  but  they  have  not  yet  been  adopted  legally 

!The  full  text  of  the  various  laws  and  regulations  will  be  found  in  the 
Appendix  to  Wolff's  paper  on  the  "So-called  International  Electrical  Units," 
Bulletin  of  the  Bureau  of  Standards  (Washington,  1901),  No.  1,  vol.  1,  pp.  61-76. 


216    EVOLUTION   OF   WEIGHTS   AND   MEASURES 

as  they  have  not  been  considered  essential,  though  strenuously 
urged  by  many  prominent  electricians. 

After  the  adoption  of  the  resolution  defining  the  electrical 
units,  at  the  Electrical  Congress  held  at  Chicago  in  1893,  and 
their  subsequent  ratification,  either  in  whole  or  in  part,  by  various 
governments,  it  was  found  that  there  were  slight  errors  in  these 
definitions,  especially  in  the  electromotive  force  of  the  Clark 
cell,  which  has  been  found  to  be  nearer  1*433  volts  than  1*434  as 
defined.  It  was  stated  by  some  physicists  that  a  cadmium 
(Weston)  cell 1  was  more  constant,  had  a  lower  temperature 
coefficient,  and  could  be  defined  with  greater  accuracy,  while 
further  researches  on  the  Clark  cell  itself  gave  a  value  for  its 
electromotive  force  somewhat  different  from  that  stated  in  the 
resolutions;  and,  in  fact,  in  Germany  the  value  1*4328  volts  was 
adopted  as  corresponding  to  the  realized  value  of  the  ohm  and 
ampere.  There  was  also  a  demand  for  new  units,  and  for  changes 
in  the  nomenclature  in  the  existing  units.  Consequently,  at  the 
Electrical  Congress  held  in  connection  with  the  St.  Louis  Exposi- 
tion, 1904,  a  chamber  of  representatives  of  various  governments 
was  in  session  to  pass  upon  these  propositions.  It  was  the 
opinion  of  the  Chamber  of  Delegates  that  these  propositions  were 
of  sufficient  character  to  warrant  a  thorough  discussion,  but,  at 
the  same  time,  the  delegates  did  not  seem  to  be  of  the  opinion 
that  they  should  be  settled  at  such  a  meeting.  Accordingly,  they 
resolved  that  a  permanent  Commission,  consisting  of  representa- 
tives from  various  governments,  should  be  convened,  and  that  to 
such  an  International  Commission  should  be  entrusted  the  decision 
of  the  matter.  Such  an  international  body  would  have  much  the 
same  duties  as  the  International  Commission  of  Weights  and 
Measures,  and,  without  doubt,  its  deliberations  and  decisions 
would  be  equally  acceptable  and  important  to  electricians  and 
physicists. 

In  concluding  this  chapter  on  electrical  units  it  is  hardly 
necessary  to  more  than  call  attention  to  the  great  benefits  that 

1  The  Weston  cell  has  for  its  electrodes  cadmium  amalgam  covered  with  a 
layer  of  crystals  of  cadmium  sulphate,  and  pure  mercury  in  contact  with  a  paste 
of-  mercurous  sulphate,  cadmium  sulphate  crystals,  and  metallic  mercury,  while 
the  electrolyte  is  a  saturated  aqueous  solution  of  zinc  sulphate  and  mercurous 
sulphate. 


INTERNATIONAL   ELECTRICAL   UNITS          21 7 

have  been  conferred  on  the  electrical  industry  throughout  the 
world  by  the  employment,  in  all  countries,  of  one  and  the  same 
system  of  units  of  measurement.  In  fact,  this  condition  has  been 
advanced  as  one  of  the  reasons  for  the  rapid  growth  of  the 
industry,  and  while  various  modifications  of  units  have  been 
demanded  and  discussed,  they  have  only  been  adopted  after  they 
have  been  determined  by  an  International  Congress.  No  nation 
or  group  of  electricians  or  engineers  has  ever  found  fault  with 
the  extensive  use  of  the  decimal  system,  and  by  the  close  con- 
nection of  electrical  units  with  the  metric  system  such  workers 
have  been  enabled  to  appreciate  the  advantages  of  the  latter,  so 
that  in  non-metric  countries  the  electrical  professions  unanimously 
are  found  eagerly  demanding  its  adoption.  In  fact,  it  has  been 
truly  said  by  a  British  electrical  engineer,1  than  whom  there  is 
no  one  more  competent  to  discuss  the  subject  in  its  many  aspects, 
that  "  so  far  as  I  am  aware  nobody  has  ever  suggested  that  it 
would  be  to  the  advantage  of  any  country  to  start  a  system  of 
electrical  units  of  its  own." 

1  Alexander  Siemens,  Presidential  Address  before  the  Institution  of  Electrical 
Engineers  of  Great  Britain,  Nov.  10,  1904,  Electrician  (London),  Nov.  11,  1904, 
p.  149. 


CHAPTEE    X. 
STANDARDS  AND  COMPARISON. 

IN  all  systems  of  weights  and  measures  based  on  one  or  more 
arbitrary  fundamental  units,  the  concrete  representation  of  the 
unit  in  the  form  of  a  standard  is  necessary,  and  the  construction 
and  preservation  of  such  a  standard  is  a  matter  of  primary 
importance.  The  reference  of  all  measures  to  an  original  standard 
is  essential  for  their  correctness,  and  such  a  standard  must  be 
maintained  and  preserved  in  its  integrity  for  purposes  of  com- 
parison by  some  responsible  authority,  which  is  thus  able  to 
provide  against  the  use  of  false  weights  and  measures.  Accord- 
ingly, from  earliest  times,  standards  were  constructed  and  pre- 
served under  the  direction  of  kings  and  priests,  and  the  temples 
were  a  favorite  place  for  their  deposit.  Later,  this  duty  was 
assumed  by  the  government,  and  to-day  in  addition  we  find  the 
integrity  of  standards  of  weights  and  measures  safeguarded  by 
international  agreement. 

The  progress  of  the  science  of  metrology  is  not  only  well 
exemplified  in  these  actual  representations  of  various  units,  but 
is  intimately  connected  with  the  construction  of  the  prototypes  of 
the  fundamental  standards.  The  mechanical  processes  and  other 
features  involved  in  their  construction  have  so  improved  with 
time  and  with  the  growth  of  physical  science,  especially  as  it 
involves  a  constantly  increasing  degree  of  exactness  in  measuring, 
that  the  subject  is  one  which  warrants  attention  in  even  a  brief 
treatise  on  weights  and  measures.  In  fact,  metrology  has  been 
defined  as :  "  That  part  of  the  science  of  measures  which  applies 
itself  specially  to  the  determinations  of  prototypes  representative 
of  the  fundamental  units  of  dimensions  and  of  mass,  of  the 
standards  of  the  first  order  which  are  derived  from  the  same,  and 
are  employed  in  experimental  researches,  aiming  at  a  high 


STANDARDS   AND   COMPARISON  219 

exactitude,  as  well  as  to  the  operations  of  diverse  natures  which 
are  the  necessary  corollaries."1 

That  a  standard  should  exactly  represent  a  unit  is  of  course 
obvious,  and  what  is  usually  the  case,  the  definition  of  the  unit  is 
derived  from  the  standard,  as  is  the  definition  of  the  British 
imperial  yard  or  the  modern  definition  of  the  meter.  Therefore 
it  is  essential  that  the  standard  should  be  so  constructed  as  to  be 
as  nearly  permanent  and  invariable  as  human  ingenuity  can  con- 
trive. As  an  example  of  the  lack  of  permanence  experienced  in 
standards,  attention  might  be  called  to  the  fact  that  the  secondary 
standards  of  the  British  yard  of  1855,  which  were  distributed  to 
the  various  nations  and  laboratories,  have  since  undergone  careful 
comparisons  and  remeasurements,  and  it  is  believed  that  in  many 
cases  their  lengths  are  not  the  same  as  when  they  were  first 
constructed.2 

While  it  is  physically  impossible  to  secure  absolute  invari- 
ability in  standards,  yet  in  their  construction  a  material  should  be 
chosen  whose  variations  are  well-determined  functions  of  one  or 
more  independent  variables  easy  to  measure.  In  practice,  these 
variations  themselves  ought  to  be  very  small,  and  the  variables 
upon  which  they  depend  susceptible  of  being  determined  with 
high  precision.  The  realization  of  these  conditions  represents 
essentially  what  has  been  accomplished  by  the  advance  of  metro- 
logical  science  so  far  as  exactness  in  standards  is  involved.  In 
the  past,  as  we  have  seen,  an  extreme  degree  of  precision  in 
measurement  was  not  essential,  nor  could  it  be  obtained  with  the 
means  at  the  disposal  of  the  scientist  or  mechanician,  but 
improvements  in  this  branch  of  science  have  been  made  to  such  an 
extent  that  within  two  centuries  the  precision  of  standards  of  length 
has  been  increased  nearly  a  thousand  fold.  With  the  growth  of 
knowledge,  it  was  realized  that  matter  varied  to  a  marked  degree 
under  the  influences  of  temperature,  pressure,  time,  and  other 
conditions,  so  that  in  consequence,  not  only  a  unit  must  be  defined 
precisely,  but  the  appropriate  standard  and  its  copies  be  so  con- 

1J.  Rene"  Benoit,  "  De  la  Precision  dans  la  Determination  des  Longuers  en 
Me"trologie,"  p.  31,  Rapports  presenter  au  Congres  International  de  Physique,  tome 
1,  Paris,  1900. 

2 See  Report,  Superintendent  U.S.  Coast  and  Geodetic  Survey,  1877.  Appendix 
12,  pp.  180-181. 


220    EVOLUTION   OF   WEIGHTS   AND   MEASURES 

structed  that  they  would  be  permanent,  invariable  and  exact.  In 
designing  and  constructing  a  standard  to  fill  these  demands  there 
would  be,  consequently,  a  number  of  conditions  to  be  satisfied. 
First,  there  would  be  the  natural  wear  of  time,  which  would  alter 
easily  the  length  of  a  measure  or  the  mass  of  a  weight,  and  could 
only  be  guarded  against  by  selecting  a  hard  and  durable  material 
which  would  resist  abrasion.  Then,  there  would  be  the  question 
of  temperature  effects,  most  important  in  all  metrological  work, 
but  hardly  realized  before  the  beginning  of  the  18th  century.  For 
it  will  be  remembered  that,  at  different  temperatures,  a  body 
varies  in  length  and  volume,  so  that  a  standard  of  length,  for 
example,  is  only  of  unit  length  at  one  stated  and  defined  tempera- 
ture, being  too  long  at  a  higher  temperature  and  too  short  at  a 
lower  temperature.  Consequently,  it  is  desirable  that  a  standard 
should  be  of  a  material  affected  as  little  as  possible  by  heat,  or, 
in  scientific  language,  having  a  low  and  regular  coefficient  of 
expansion,  and  it  is  essential  that  this  amount  of  expansion 
should  be  known  accurately,  so  that  in  case  the  standard  is  used 
at  other  temperatures  than  that  of  the  definition,  the  amount  that 
it  is  too  large  or  too  small  may  be  taken  into  consideration  and 
allowed  for,  as  by  knowing  accurately  and  applying  the  factor 
which  represents  the  variation  in  length,  a  measurement  may  be 
made  as  exact  as  the  original  measurement  on  which  the  standard 
is  based.  It  is  therefore  necessary  to  exclude  from  consideration 
materials  having  coefficients  of  expansion  which  vary  con- 
siderably at  different  temperatures,  or  which  expand  at  a 
different  rate  from  that  with  which  they  contract. 

The  prime  condition  of  a  standard  of  length,  and  the  same  is 
essentially  true  of  standards  of  mass,  is  that  it  should  consist  of  a 
single  bar,  or  piece  of  a  single  material,  avoiding  any  joining  of 
several  elements,  such  as  by  screws  or  by  soldering.  In  fact,  the 
method  used  at  the  beginning  of  the  19th  century,  whereby  a  strip 
of  silver  was  inlaid  on  a  brass  bar,  as  in  the  Troughton  scale,  after 
the  fashion  of  the  graduated  circles  of  various  modern  instruments, 
was  soon  found  unsuitable  for  the  standards  of  higher  precision 
which  were  demanded.  The  material  selected  should  not  only  be 
hard  and  highly  elastic,  but  should  have  a  surface  that  can  be 
polished  readily,  and  engraved  with  the  marks  of  terminal  limits, 
or  of  the  divisions  of  the  unit.  For  many  years  it  was  customary 


STANDARDS   AND   COMPARISON  221 

to  construct  the  standards  of  iron  or  of  brass — materials  which 
were  easily  oxidizable,  and  which  were  with  difficulty  obtained  in 
a  pure  and  constant  condition.  For  the  standard  of  the  meter, 
known  as  the  Meter  of  the  Archives,  platinum  was  used  ;  but  later, 
the  material  best  suited  for  a  standard  was  found  to  be  an  alloy 
of  platinum  and  iridium,  and  such  was  used  for  the  international 
prototype  meter  and  kilogram  and  the  national  standards  copied 
therefrom.  This  material,  however,  being  extremely  expensive, 
cannot  be  used  generally  where  secondary  standards  for  ordinary 
exact  measurements  are  desired,  nor  can  rock  crystal  of  which  a 
few  standards  of  mass  have  been  constructed. 

A  recent  study  of  alloys,  however,  has  resulted  in  finding 
materials  which  possess  many  of  the  desired  properties,  such  as 
hardness  and  durability,  and  at  the  same  time  have  a  low 
coefficient  of  expansion.  One  of  the  most  recent  of  these,  known 
as  invar,  has  resulted  from  experiments  carried  on  at  the 
International  Bureau  of  Weights  and  Measures,  and  has  been 
developed  to  a  high  degree  of  usefulness  by  M.  Guillaume.  This 
metal,  which  consists  of  36  parts  of  nickel  to  64  of  steel,  has  been 
found  available  for  measuring  rods  and  wires  for  use  in  geodetic 
operations,  and  seems  destined  to  occupy  a  much  wider  field  in 
the  future.  Wires  for  measuring  base  lines  made  of  this  alloy 
have  been  found  to  possess  a  coefficient  of  expansion  in  some 
cases  as  low  as  '0000001  for  a  degree  centigrade.1  In  1900  invar 
standards  and  gauges  were  put  on  the  market,  and  for  all  prac- 
tical purposes  permitted  the  disregarding  of  temperature  effects. 
In  fact,  it  has  been  proposed  to  employ  a  heavy  bar  of  this 
material  as  the  support  of  the  observing  microscopes  in  a  com- 
parator. Invar,  however,  is  not  quite  steady  and  constant  and 
cannot  be  used  for  primary  standards.  In  accurate  surveying 
such  standards  should  be  determined  just  before  and  after  using 
in  the  field. 

From  the  early  standards  of  length  rectangular  or  cylindrical 
in  form,  much  improvement  has  been  made  and  care  is  now 
taken  that  the  cross-section  of  the  bar  shall  be  of  such  design 

iSee  Guillaume,  "  Les  Process  Rapides  de  la  G&>d&sie  Moderne,"  La  Nature 
(Paris),  1904,  No.  1640,  p.  339,  and  No.  1643,  p.  395;  id.,  Lea  Application*  de* 
Aciers  au  Nickel,  avec  un  Appendice  sur  la  TMorie  des  Aciers  au  Nickel  (Paris, 
1904)  ;  id.,  La  Convention  du  Metre  (Paris,  1902),  pp.  127  and  233. 


222    EVOLUTION   OF   WEIGHTS    AND   MEASURES 

that  not  only  it  shall  possess  maximum  strength,  but  especially 
that  it  will  resist  deformation  by  bending,  which  in  accurate 
measurements  may  cause  considerable  error.  Thus  in  a  linear 
scale  of  considerable  length  as  compared  with  its  breadth  and 
thickness  and,  let  us  say,  of  rectangular  section,  where  the 
divisions  are  on  the  upper  surface,  it  will  be  obvious  that  if  it  is 
so  supported  that  the  ends  hang  lower  than  the  centre,  the  upper 
surface  will  form  a  convex  curve,  and  the  particles  of  the  material 
lying  in  such  a  surface  will  be  stretched  apart,  and  the  distance  A 
to  B  will  be  greater  than  when  the  bar  is  straight  as  under 
normal  conditions. 


If  the  ends  of  the  scale  were  supported,  rather  than  the  centre, 
the  opposite  conditions  would  prevail,  and  the  marked  distance 
will  be  too  short.  This  was  recognised  by  Captain  Kater,  who 
proposed  the  employment  of  a  scale  of  small  thickness  which  was 
placed  on  a  base  whose  surface  was  perfectly  plane.1  A  better 
solution  of  the  difficulty  was  to  use  the  neutral  fibres,  as  shown 
by  the  dotted  line  CD,  and  for  this  purpose  the  British  standard 
of  1855  was  constructed,  as  shown  on  pages  245  and  246,  where  the 
unit  distance  is  measured  between  lines  on  polished  gold  plugs,  set 
in  two  holes  or  wells,  so  that  they  lie  in  this  so-called  neutral  plane. 
This  idea  was  more  perfectly  carried  out  in  the  standards  of 
the  International  Metric  Commission,  having  the  X-section  as 
shown  on  page  254,  where  the  construction  is  such  that  the  bar 
possesses  maximum  rigidity  with  the  minimum  material  and  the 
neutral  plane  in  the  line  standard  is  easily  accessible  for  measure- 
ments throughout  its  length.  In  standards  for  small  lengths,  such 
as  the  decimeter,  such  considerations  as  a  desirable  type  of  cross- 
section  and  the  placing  of  the  divisions  in  a  neutral  plane, 
naturally  do  not  require  careful  consideration  and  can  practically 

1See  Kater,  "Investigation  of  the  Curvature  of  Bars,  produced  by  the  In- 
equalities of  the  supporting  surface,"  Phil.  Trans.,  1830,  p.  359.  See  also  W.  A. 
Rogers,  Proc.  Amer.  A  cad.  Arts  and  Sciences,  vol.  xv.  1879-80,  p.  292. 


STANDARDS   AND   COMPARISON  223 

be  neglected,  but  in  meter  or  yard  standards  it  is  an  important 
consideration. 

Then,  as  regards  the  actual  means  of  denoting  the  distance,  we 
may  have  end  standards  (ttalon  h  louts)  and  line  standards  (ttalon 
&  traits).  The  end  standard  represents  the  given  unit  by  the 
distance  between  the  extreme  boundary  surfaces,  as  in  the  case  of 
any  ordinary  rule,  or  in  the  case  of  the  inside  measure, — the 
distance  between  the  interior  surfaces  of  two  extended  arms, — the 
object  being  to  secure  better  protection  for  the  surfaces  employed 
for  measurement,  and  at  the  same  time,  to  furnish  a  ready  means 
of  comparing  end  measures  with  a  standard,  by  simply  bringing 
them  within  the  space  included  between  the  terminal  arms. 
With  the  other  form  of  standard,  the  limits  of  the  distance  are 
indicated  by  lines  or  sometimes  dots.  The  line  standard,  of 
course,  can  be  used  with  a  microscope  with  cross-hairs,  or  a 
micrometer  microscope,  much  more  readily  than  an  end  standard, 
as  it  is  possible  to  effect  an  exact  setting  on  even  a  coarse 
line  with  much  greater  accuracy  than  on  an  edge,  which 
though  imperceptibly  worn  to  the  naked  eye,  would  appear 
rough  and  indistinct  when  magnified  by  the  microscope. 

The  line  standard  possesses  a  distinct  advantage,  where  it  is 
divided  throughout  its  whole  length,  as  is  usually  the  case,  since 
it  is  readily  comparable  with  its  own  sub-divisions  and  with 
smaller  standards.  On  the  other  hand,  the  end  standard  con- 
stitutes merely  a  standard  for  a  single  length,  and  does  not  lend 
itself  to  direct  comparisons  with  the  ordinary  standards  of  other 
lengths  in  the  laboratory  or  testing  bureau,  which  in  the  case  of 
metric  scales  are  usually  divided  into  millimeters,  with  the  centi- 
meters and  decimeters  suitably  marked.  With  a  standard  so 
divided,  standards  of  measure  for  other  distances  besides  the 
greatest  one  marked  on  its  surface  must  be  supplied. 

In  spite  of  the  general  tendency  to  use  a  line  standard,  rather 
than  an  end  standard,  Bessel,  in  1835,  when  he  was  preparing  a 
standard  based  on  the  seconds  pendulum  at  Koenigsberg,  used  a 
steel  bar  with  sapphires  set  in  its  ends,  to  form  a  standard  of  length. 
This  standard  of  Koenigsberg  was  used  as  a  basis  for  numerous 
measurements  of  base  lines  in  geodetic  surveys  in  Europe.1 

Though  the  line   standard  forms   the   most   suitable,  and   in 

1  P.  9,  Guillaume,  La  Convention  du  Metre. 


224    EVOLUTION   OF   WEIGHTS   AND   MEASURES 

fact  the  only,  standard  for  a  modern  prototype,  and  even  for 
secondary  purposes,  there  are  nevertheless  occasions  where  stan- 
dards of  the  end  type  can  be  conveniently  used.  Especially  is 
this  the  case  in  mechanical  engineering,  where  various  gauges 
and  shop  standards  must  be  constructed  so  as  to  be  used  readily 
in  the  tool-room  or  machine  shop  for  accurate  measurements. 
The  methods  of  comparison  are  essentially  similar  to  those 
employed  in  comparing  line  standards.  However,  certain 
variations  of  methods  have  been  introduced,  since  it  is 
necessary  to  consider  the  terminal  faces,  which  are  susceptible 
of  wear  and  must  be  protected  carefully.  In  addition  to  the 
use  of  the  microscope  comparator,  which  is  described  below, 
in  connection  with  line  standards,  there  are  three  methods 
which  can  be  used  for  this  purpose,  as  follows : 

First,  the  method  of  direct  contact,  which,  while  the  simplest, 
can  also  be  made  very  accurate  if  properly  used. 

Second,  by  reflection  of  an  object  at  the  terminal  surface. 

Third,  by  interference  fringes  which  are  produced  at  the 
ends  of  the  scale  to  be  measured. 

In  the  method  of  contact,  which  is  ordinarily  employed 
where  a  high  degree  of  precision  is  unnecessary,  it  is  usual 
to  employ  such  simple  measuring  devices  as  a  screw  micro- 
meter, or  a  spherometer,  or  some  less  accurate  form  of  instru- 
ment, such  as  calipers  or  a  beam  compass.  The  second  and 
third  methods  are  optical,  and  must  be  executed  by  a  trained 
physicist ;  but  they  increase  materially  the  range  of  precision, 
and  can  afford  results  more  accurate  than  are  obtained  in 
comparing  line  standards. 

The  method  of  reflection  was  employed  in  comparing  the 
Meter  of  the  Archives,  an  end  standard,  with  the  provisional 
meter  for  the  construction  of  the  international  prototype,  and 
also  subsequently  in  the  standardizing  of  certain  end  standards 
of  platinum-iridium,  which  were  given  to  such  nations  as  had 
ordered  them.  This  method  consisted  in  observing  the  dis- 
placement of  the  reflection  of  a  line  at  the  terminal  surface 
of  the  bar;  and  while  under  certain  circumstances  it  was 
exact,  it  required  a  study  of  the  objectives  of  the  microscope 
and  other  features  in  order  to  insure  its  accuracy. 

Employing   this   method,  in   1881-82,  a  series  of  comparisons 


STANDARDS   AND   COMPARISON  225 

of  the  new  standards  was  made  at  the  Conservatoire  des  Arts 
•et  Metiers  with  the  Meter  of  the  Archives,  taking  into  con- 
sideration most  carefully  the  question  of  temperature.  It  was 
found  that  these  comparisons,  when  reduced  to  0  degrees  C., 
gave  an  accuracy  of  '6  of  a  micron  for  each  standard. 

In  the  method  of  interference  use  is  made  of  the  phenomenon 
of  Newton's  rings,  whereby  interference  of  light  follows  differ- 
ences in  the  path  of  a  beam,  such  as  may  be  produced  by 
reflection  from  two  different  surfaces.  It  is  necessary  to  have 
a  fixed  and  determined  surface  as  a  plane  of  reference,  and  then 
to  consider  the  difference  in  the  fringes  that  are  produced 
by  light  falling  on  two  other  surfaces  at  different  times. 

Considering  now  a  line  standard  constructed,  of  approved 
material  and  cross-section,  it  is  naturally  of  primary  import- 
ance to  provide  the  marks  accurately  limiting  the  distance. 
These  marks  or  traces  are  usually  made  with  a  diamond,  and 
are  transverse  to  the  axis  of  the  bar.  The  method  employed 
is  to  place  the  bar,  with  the  standard  by  which  it  is  graduated, 
on  the  carriage  of  a  special  piece  of  apparatus,  such  as  a  com- 
parator or  dividing  engine,  which  will  be  described  below  more 
fully,  with  the  cross-hairs  of  one  of  the  microscopes  accurately 
over  the  line  of  the  standard  scale.  After  a  mark  is  made 
on  the  scale  to  be  graduated,  both  scales  are  moved  until  the 
second  mark  of  the  standard  scale  is  under  the  cross-hairs, 
and  another  ruling  is  then  made  by  the  diamond.  Or  the 
scales  may  remain  stationary  and  the  microscope  and  tracing 
•device  be  moved. 

To  divide  a  scale  into  millimeters  or  other  divisions  the 
dividing  engine  is  employed,  an  instrument  in  which  the 
•essential  feature  consists  of  an  accurately  constructed  screw, 
whose  pitch  (i.e.  distance  between  threads),  as  well  as  its 
•constant  and  periodic  errors,  are  known  to  a  high  degree  of 
precision.  This  screw,  working  in  a  suitable  nut,  moves  a 
table  along  a  heavy  metal  supporting  bench,  and  a  metal  or 
glass  bar  on  this  table  can  be  moved  forward  by  regular  and 
successive  intervals  of  length.  Above  the  table  is  a  tracing 
device  operating  in  a  fixed  vertical  plane,  and  by  this  means 
the  desired  divisions  may  be  inscribed  on  the  bar.  Apparatus 
of  this  kind  has  been  constructed  which  is  entirely  automatic 

p 


226    EVOLUTION   OF   WEIGHTS   AND   MEASURES 

in  its  movements,  and  which  is  able  to  mark  the  divisions 
in  millimeters  on  a  scale  a  meter  in  length.  Such  machines 
have  means  of  correcting  the  errors  in  the  screw,  whether 
they  are  constant  or  occur  at  different  intervals  of  its  length,. 
and  also  devices  permitting  corrections  for  temperature.  Often 
these  machines  are  driven  by  an  electric  motor,  and  even  the 
differences  in  length  of  the  marks  denoting  divisions  of  the 
scale — as,  for  example,  at  every  tenth  millimeter — are  made 
longer  automatically.  A  meter  scale  divided  into  millimeters 
can  be  ruled  with  a  machine  of  this  description  in  the  Inter- 
national Bureau  of  Weights  and  Measures,  in  about  sixteen  hours, 
with  an  accuracy  of  two  or  three  microns  for  each  division.1 

With  the  dividing  engine  or  ruling  machine  of  the  late  Pro- 
fessor H.  A.  Kowland  of  the  Johns  Hopkins  University,  designed 
for  constructing  diffraction  gratings  for  spectroscopic  work  rather 
than  for  making  linear  scales,  as  many  as  20,000  lines  to  the  inch,, 
787'5  to  the  millimeter,  could  be  ruled  on  speculum  metal,  and 
gratings  having  as  many  as  120,000  lines  have  been  made  where 
the  estimated  error  between  any  two  lines  was  not  thought  to 
exceed  2oooooo  °^  an  incn>  or  nearly  the  8 0 ^ 0 0  of  a  millimeter.2 

To  secure  the  best  results,  the  surface  of  the  standard  or  scale 
on  which  the  lines  are  traced  should  be  highly  polished,  and  great 
care  should  be  taken,  not  only  in  the  choice  of  the  diamond  or 
tracing-tool,  but  in  the  actual  operation.  The  line  made  should 
be  clear  and  sharp,  not  broader  than  is  absolutely  necessary,  and 
not  appearing  rough  and  indistinct  when  seen  under  the  micro- 
scope. In  the  national  standard  prototypes  of  the  meter  this  line 
measures  from  6  to  8  microns  in  width,  but  after  it  had  been 
ruled,  it  was  thought  that  a  much  narrower  line,  say  2  or  3 
microns,  could  have  been  used  with  advantage, — securing,  of 
course,  a  sufficient  depth  to  insure  the  permanent  preservation  of 
the  line.  On  both  sides  of  the  line  at  a  distance  of  '5  mm. 
are  two  parallel  and  similar  lines,  the  distance  between  them 

!M.  Guillaume  says,  "It  is  essential  hi  order  to  get  very  good  lines  to  trace 
very  slowly,  and  in  the  studies  made  at  the  Bureau  International  it  has  been 
found  useful  to  trace  the  1000  lines  of  the  meter  in  millimeters  in  about  16  hours. 
The  inaccuracy  in  the  position  of  either  end  line  does  not  exceed  two  or  three 
microns,  but  of  course  the  error  of  every  interval  of  1  mm.  is  much  smaller." 

2  See  The  Physical  Papers  of  Henry  A.  Rowland  (Baltimore,  1902),  pp.  506-51  !„ 
691-697. 


STANDARDS   AND   COMPARISON  227 

forming  a  standard  millimeter  at  each  end  of  the  scale,  which 
furnishes  a  check  on  the  micrometer  of  the  microscopes  of  the 
comparator  used  to  compare  the  scales.  These  transverse  lines 
are  crossed  by  two  longitudinal  lines  parallel  to  the  axis  of  the 
bar,  and  distant  from  each  other  *2  of  a  millimeter.  Between 
the  intersections  of  these  lines  with  the  transverse  lines  is  where 
the  standard  distance  is  measured. 

The  important  part  played  by  temperature  in  exact  determina- 
tions and  comparisons  of  standards  of  length,  as  well  as  of  mass, 
of  course  involves  a  means  of  measuring  such  temperatures.  This 
subject  has  received  increasing  attention  in  the  course  of  time, 
and  it  has  been  realized  that  exactitude  in  constructing  standards 
of  length  is  only  possible  where  the  most  accurate  methods  of 
temperature  measurements  are  employed,  as  the  changes  in  length 
or  volume  with  temperature  of  course  produces  marked  variations 
from  the  standard  unit.  Since  a  linear  unit  is  represented  by  the 
length  of  a  standard  or  bar  of  metal  at  a  fixed  and  defined  temper- 
ature, at  no  other  temperature  will  this  bar  have  the  standard 
length,  and  consequently  its  exact  length  at  such  other  tempera- 
ture can  only  be  ascertained  by  knowing  the  amount  that  it 
expands  for  a  unit  (degree)  of  temperature,  and  the  precise 
temperature  at  which  the  measurement  is  made.  Accordingly, 
two  thermometric  measurements  of  great  precision  are  involved, 
one  in  determining  the  expansion  of  the  material  forming  the 
standard,  or  obtaining  the  coefficient  of  expansion  of  the  bar, 
and  the  other,  in  measuring  the  temperature  at  which  the  bar  is 
used.  Now  as  the  coefficient  of  expansion  enters  as  a  direct 
factor  in  determining  the  exact  length  of  a  standard,  it  is 
necessary  to  consider  how  far  we  can  depend  upon  its  accuracy, 
and  to  realize  that  if  this  factor  cannot  be  trusted  beyond  a 
certain  figure  of  decimals,  then  refinement  of  measuring  with  the 
micrometer  is  quite  superfluous. 

In  the  first  attempts  at  accurate  measurement  and  comparison 
of  standards,  as  soon  as  temperature  effects  began  to  be  considered, 
mercury-in-glass  thermometers  were  used,  and  in  them  for  many 
years  a  confidence  was  placed,  which  has  been  since  found 
entirely  unwarranted.  The  gravity  of  this  matter  was  realized 
by  physicists  toward  the  middle  of  the  19th  century,  and  at  the 
time  of  the  construction  of  the  international  standards,  it  was 


228    EVOLUTION   OF  WEIGHTS   AND   MEASURES 

considered  necessary  to  undertake  a  complete  study  of  the 
mercury-in-glass  thermometer,  and  find  within  what  limits  its 
accuracy  could  be  trusted.  So  many  sources  of  error  were  found 
in  the  instruments  as  then  constructed,  due  to  the  material  used, 
and  to  differences  in  its  behaviour  at  different  temperatures,  as 
well  as  to  the  difference  in  the  coefficient  of  expansion  of  mercury 
at  different  temperatures,  that  it  was  found  necessary,  after  a 
most  thorough  investigation,  to  adopt  a  gas  thermometer  in  which 
hydrogen  was  used  as  the  expanding  fluid.  In  this  the  expansion 
of  the  gas  indicates  the  temperature,  and  within  certain  limits  it 
is  far  more  accurate  than  the  mercurial  thermometer.  The  latter, 
however,  when  carefully  studied  and  calibrated,  can  be  referred  to 
the  hydrogen  scale  with  sufficient  exactness  for  use  at  ordinary 
temperatures.  For  purposes  of  standardizing,  it  has  been  found 
necessary  to  refer  all  temperature  measurements  to  the  hydrogen 
thermometer,  and  the  study  of  exact  thermometry  made  at  the 
International  Bureau  of  Weights  and  Measures,  has  been  one  of 
its  most  important  scientific  works.  It  has  served  to  increase  the 
accuracy  of  the  present  standard  of  length  and  of  mass,  as  well  as 
to  raise  materially  the  degree  of  precision  in  all  measurements  in 
science  in  which  temperature  enters  as  a  factor.1 

Fundamental  standards  or  prototypes  are  of  course  not  avail- 
able for  general  work,  even  where  high  precision  is  demanded, 
but  they  must  serve  only  as  a  basis  for  the  construction  and 
testing  of  secondary  standards  which  are  divided  throughout  their 
entire  length.  These  are  necessary  for  many  purposes,  and  can 
be  used  under  conditions  involving  more  or  less  wear. 

The  question  of  the  permanence  of  these  fundamental 
standards,  or  more  particularly  that  of  the  international  prototype 
meter  is  of  primary  importance.  New  methods  involving  greater 
exactness  in  measurements  and  comparisons  would  avail  little  if 

1  Good  modern  mercury  thermometers  made  of  hard  glass  alloy  are  of  great 
accuracy  at  moderately  high  temperatures,  but  their  scale  though  very  well 
defined  and  reproducible  is  an  arbitrary  one  and  has  no  fixed  relation  with 
theoretical  phenomena,  as  is  the  case  with  the  gas  thermometer — Guillaume. 
See  Benoit,  p.  75,  Rapports  Congres  International  de  Physique,  tome  i.  Paris, 
1900.  Guillaume,  La  Convention  du  Metre,  Paris,  1902,  p.  26,  etc.,  for  resume 
of  thermometric  studies  at  the  International  Bureau  of  Weights  and  Measures ; 
Traite  de  la  Thermometrie  de  Precision.  Paris,  1889.  Travaux  et  Mdmoires, 
Bureau  International  des  Poids  et  Mesures,  vol.  i.-vi.,  x.,  xii.,  xiii. 


STANDARDS   AND   COMPARISON  229 

changes  were  taking  place  in  the  material  of  the  standard  bar 
which  would  produce  variations  in  its  length.  Evidence  that 
has  accumulated  in  almost  twenty  years'  experience  with  the 
national  standard  meter  bars  does  not  indicate  any  substantial 
changes  that  should  give  cause  for  anxiety  in  this  respect,  but  at 
the  same  time,  the  physicist  is  hardly  in  a  position  to  guarantee 
this  permanence  for  a  longer  period  of  time,  such  as  a  century. 
Recourse  must  be  had,  therefore,  to  a  series  of  comparisons 
of  other  standards  among  themselves  and  of  providing  new  means 
by  which  the  integrity  of  the  standard  may  be  safeguarded. 
The  most  satisfactory  of  these  auxiliary  means  of  protection  is 
the  reference  of  the  standard  meter  to  a  wave-length  of  light, 
according  to  the  method  devised  by  Professor  A.  A.  Michelson 
and  applied  at  the  Bureau  International  des  Poids  et  Mesures,  to 
which  reference  will  be  made  in  the  course  of  a  few  pages.  Thus 
to-day  the  permanence  of  the  meter  is  assured  in  that  it  is  defined 
in  terms  of  a  wave-length  of  cadmium  light,  with  an  exactitude 
of  one  part  in  1,000,000  or,  in  other  words,  of  a  micron.1 

In  comparing  standards  of  length  the  earliest  scientific  device 
employed  was  the  use  of  some  form  of  calipers  or  beam  compass. 
Thus  in  comparing  an  outside  end  standard  with  an  inside  end 
standard,  by  placing  the  former  between  the  projecting  ends  of 
the  latter,  a  measurement  could  readily  be  made.  For  com- 
parisons of  this  kind,  the  inside  end  standards  constructed  of 
metal  were  frequently  embedded  in  a  masonry  wall  at  some 
central  and  convenient  point  in  a  city.  In  comparing  the  toise 
of  Peru  with  that  of  the  Grand  Ch&telet,  we  are  told  by  the 
Astronomer  Lalande  that  the  microscope,  in  connection  with  a 
beam  compass  having  very  fine  points,  was  used  as  early  as 
1735,  and  we  also  know  that  a  similar  device  where  the 
jaws  or  points  were  moved  by  micrometer  screws  with  divided 
heads  was  employed  in  England  by  Graham,  in  1742,  in 
making  his  comparison  of  standards  of  length.2  In  the  earliest 
comparisons  involved  in  the  original  determination  of  the  meter 
and  the  construction  of  the  standard  bars  used  for  measuring 

1  Benoit,  p.  68,  Rapports  Congres  International  de  Physique,  vol.  i.    Paris,  1900. 
2 See  "Description  of  Standards  and  Use  of  Beam  Compasses,"  Philosophical 
Transactions,  1742-1743,  vol.  xlii.     London. 


230    EVOLUTION   OF   WEIGHTS   AND   MEASURES 

the  bases,  the  various  scales  to  be  measured  and  compared 
were  placed  on  a  long  plate  of  brass,  having  a  fixed  terminal 
piece  at  one  end,  with  which  the  ends  of  the  scales  were  placed 
in  contact.  Differences  of  length  were  determined  by  means  of  a 
moving  contact  block  and  a  small  scale  carefully  divided.  This 
device,  known  as  the  rule  of  comparison,  or  the  comparator  of 
Borda  and  also  of  Lenoir,  which  was  believed  for  many  years  to 
have  been  lost,  was  discovered  by  M.  Wolf,1  and  is  now  preserved 
in  the  Observatory  of  Paris.  It  consists  of  a  heavy  strip  of 
copper,  some  13  pieds  (4'225  meters)  long,  30  lignes  (678  centi- 
meters) in  width,  and  4  lignes  ('9  centimeter)  in  thickness.  The 
movable  piece  is  a  smaller  scale  of  copper,  about  6  feet  in  length, 
and  divided  into  ten  thousandths  of  a  toise.  It  was  movable 
along  the  copper  bar,  and  with  it  an  exact  reading  of  the  length 
of  the  scales  to  be  compared  could  be  made.  There  were  verniers 
ruled  on  the  copper  bar  at  different  points,  such  as  12  pieds  from 
the  extremity,  for  the  comparison  of  geodetic  base  bars  of  2  toises 
length ;  at  6  pieds  for  the  comparison  of  toise  standards ;  at  3 
pieds  for  the  comparison  of  meters,  etc.  The  verniers  were 
divided  to  read  to  tenths,  so  that  it  was  possible  to  obtain  the 
l^j  part  of  the  length  of  a  toise.2 

In  this  way  a  degree  of  precision  equal  to  about  -^^  of  a 
ligne  ('01  mm.)  was  obtained,  which  was  practically  ten  times  that 
attained  in  the  comparisons  of  the  toise  of  Peru  and  that  of  the 
Grand  Chatelet  half  a  century  before.  However,  even  greater 
precision  was  demanded  at  this  time,  and  accordingly,  a  lever 
comparator  was  constructed  by  Lenoir,  in  which  the  long  arm  of 
a  lever  magnified  the  distance  traversed  by  a  movable  contact  piece 
in  connection  with  a  shorter  arm,  with  the  result  that  it  was  pos- 
sible to  read  even  smaller  differences  than  those  mentioned  above.3 

The  next  step  marking  progress  and  increased  accuracy  in  the 
comparison  of  standards  was  the  use  of  the  micrometer-microscope 
which  was  devised  by  Troughton,  of  London,  and  was  first  em- 
ployed by  Sir  George  Shuckburgh,  in  1796-8,  in  the  measurement 
of  some  line  standards,  which  were  then  beginning  to  be  employed 

1  See  Annales  de  I'Observatoire  de  Paris;  Mdmoires,  vol.  17,  p.  C  32. 
2Bigourdan,  p.  86,  Le  Systeme  Metrique,  Paris,  1901. 

3  Benoit,  p.  34,  Rapports  presentes  au  Congres  International  de  Physique,  vol.  i. 
Paris,  1900. 


STANDARDS   AND   COMPARISON  231 

in  metrology.1  This  device  has  since  played  an  important  part 
in  all  such  comparisons,  and  the  micrometer-microscope,  in 
improved  form,  figures  in  many  instruments  for  this  purpose.  In 
•Shuckburgh's  comparator,  the  two  microscopes  were  arranged 
vertically  on  a  metallic  bar,  and  in  one  there  were  fixed  cross- 
hairs, and  in  the  other,  a  movable  system  of  cross-hairs  connected 
with  the  screw  of  a  micrometer.  The  divisions  of  the  head  of 
this  screw  corresponded  to  ten  thousandths  of  an  English  inch. 
The  method  of  operating  was  to  adjust  one  of  the  scales  so  that 
the  image  of  its  line  should  appear  at  the  cross-hairs  of  one  of  the 
microscopes,  the  cross-hairs  being  set  at  the  focus  of  the  objective. 
The  other  microscope  would  be  so  adjusted  that  its  cross-hairs 
would  coincide  with  the  image  of  the  line  at  the  opposite  end  of 
the  scale,  or  in  case  of  a  comparison  with  end  standards,  the  cross- 
hair would  be  set  on  the  ends  themselves.  In  making  a  com- 
parison, a  second  scale  was  substituted  for  the  first,  and  was 
placed  under  the  microscopes  in  the  same  position,  one  of  the 
lines,  or  the  extremity  of  the  scale  (in  case  it  were  an  end 
standard)  being  made  to  take  a  position  so  that  its  image  would 
correspond  with  the  cross-hairs  of  the  first  microscope.  If  the 
other  division  were  exactly  equivalent  to  that  of  the  first  scale,  it 
would  occupy  the  same  position  in  the  field  of  the  second  micro- 
scope, but,  in  case  there  was  a  difference,  this  difference  could  be 
measured  by  moving  the  movable  cross-hairs  with  the  micrometer 
screw.  The  micrometer-microscope  of  Sir  George  Shuckburgh 
was  capable  of  reading  to  "0001  of  an  inch,  or  the  ^  of  a  milli- 
meter, and  with  this  apparatus  he  made,  in  1802,  a  comparison 
between  the  British  and  French  standards. 

This  idea  for  a  comparator  underwent  subsequent  improvements 
about  1804  at  the  hands  of  Baily,  also  of  England,  who  employed 
in  his  apparatus,  two  microscopes,  each  provided  with  a  micro- 
meter and  with  an  achromatic  objective,  by  means  of  which 
the  image  was  made  clearer  and  the  magnification  increased. 
He  also  devised  a  method  whereby  the  scales  could  be  slid 
under  the  microscopes,  without  touching  them  with  the  hands, 
by  arranging  a  carriage  on  a  frame  independent  of  the  microscopes. 
While  this  apparatus  contained  important  improvements,  never- 
theless, in  its  construction,  it  lacked  in  solidity,  and  at  the 

1  Philosophical  Transactions  (London),  1798,  p.  137. 


232    EVOLUTION   OF   WEIGHTS   AND   MEASURES 

same  time  was  without  adequate  means  of  preserving  the- 
temperature  of  the  rules  constant.  Accordingly,  the  commission 
charged  with  the  construction  of  the  British  Imperial  Standards,, 
in  1843,  made  important  improvements  in  the  comparator, 
supplying  the  desired  rigidity  and  strength  by  means  of  a 
solid  foundation  for  the  microscopes,  and  providing  for  enclosing 
the  rules  to  be  compared  in  a  double-lined  box,  whose  tempera- 
ture was  maintained  constant  at  the  desired  temperature  by 
a  circulation  of  water. 

In  France,  also,  the  work  of  constructing  and  comparing 
standards  of  length  developed,  and  the  progress  towards  exact- 
ness made  in  that  country  during  the  nineteenth  century,  was 
due  in  large  part  to  the  placing  the  service  of  weights  and 
measures  in  charge  of  the  Conservatoire  des  Arts  et  Metiers.. 
There  was  constructed  for  this  institution,  by  Gambey,  a  com- 
parator with  longitudinal  displacement,  which  permitted  the 
comparison  of  both  end  and  line  standards,  and  at  the  same 
time  allowed  the  defining  lines  to  be  marked  upon  them.  The 
result  of  improvements  and  the  activity  of  this  establishment 
was  that  much  was  accomplished  in  the  semi-scientific  and 
industrial  application  of  exact  measurements,  and  the  weights 
and  measures  of  France  were  brought  to  a  higher  degree  of 
precision. 

In  the  United  States,  also,  important  comparisons  were  made 
of  the  various  scales  presented  by  the  French  and  British 
Governments,  with  those  in  the  Coast  and  Geodetic  Survey^ 
But  neither  instruments  nor  methods  represented  any  striking 
departures  from  European  practice,  though  the  work  itself  was 
up  to  the  high  scientific  standard  maintained  by  this  bureau 
and  was  favorably  commented  on  abroad.  A  useful  and 
accurate  comparator,  still  in  use,  was  constructed  by  Saxton. 
and  was  employed  in  making  the  early  standards  of  length.1 

While  there  have  been  no  fundamental  improvements  in 
the  idea  underlying  the  operation  of  comparing  standards, 
within  the  last  half-century,  nevertheless  by  various  mechanical 
improvements  and  refinements,  the  range  of  accuracy  has  been 
notably  increased,  so  that  to-day  the  modern  comparator 
represents  an  instrument  susceptible  of  great  precision  in  the 
1  Executive  Doc.  27,  34th  Congress,  3rd  Session. 


STANDARDS   AND   COMPARISON  23S 

hands  of  a  competent  observer.  The  prime  requisite  of  a  com- 
parator designed  for  such  purposes  as  the  comparison  of  a 
prototype  with  national  or  other  standards,  is  its  stability,  and 
for  that  purpose  the  instrument  is  generally  mounted  on  piers 
of  solid  masonry,  which  are  independent  of  the  structural  walls* 
of  the  building  in  which  it  is  placed.  It  is  essential  that  such  a 
building  should  be  located  in  a  place  free  from  vibrations  and 
disturbances,  such  as  would  be  produced  by  the  traffic  of  a  busy 
street,  or  by  machinery,  or  by  a  railway.  The  micrometer- 
microscopes  are  mounted  on  heavy  castings,  set  on  separate  piers 
placed  at  approximate  distances,  if  the  comparator  is  to  be  used 
for  the  comparison  of  standards  of  a  single  unit,  as,  for  example, 
meter-bars.  If,  on  the  other  hand,  the  comparator  is  of  a 
universal  character,  and  must  be  used  in  the  comparison  of 
various  lengths,  then  the  microscopes  must  be  mounted  on 
solid  carriages,  which  are  capable  of  being  moved  along  some 
sort  of  a  solid  frame-work  or  firmly  mounted  beam.  Equally 
important  with  the  microscopes  is  the  arrangement  for  carrying 
the  scales  which  are  to  be  compared.  Some  means  must  be- 
provided  to  place  them  successively  in  the  same  position  beneath 
the  microscopes,  so  that  the  difference  in  their  length  may  be 
determined  by  means  of  the  micrometers.  These  scales  must  be 
maintained  at  the  same  temperature,  and  must  be  examined 
under  practically  the  same  conditions.  This  involves,  first,  the 
absolute  uniformity  of  the  temperature  of  the  apparatus  itself, 
and  for  this  purpose  it  should  be  installed  in  a  room  where 
direct  sunlight  cannot  penetrate  and  be  surrounded  by  corridors,, 
enabling  a  constant  temperature  to  be  maintained.  This  requires^ 
naturally,  an  apartment  of  a  considerable  extent,  provided  with 
thick  walls,  and  specially  designed  doors  and  windows,  as  well 
as  various  devices  for  maintaining  automatically  the  desired 
degree  of  temperature.  The  entire  instrument  may  be  surrounded 
by  a  box  through  which  penetrate  only  the  eye-pieces  of  the 
microscopes  and  the  handles  controlling  the  various  parts  of  the 
mechanism. 

To  keep  the  scales  at  the  same  temperature  there  is  a  movable 
carriage  which  carries  a  double-walled  box  containing  water. 
In  this  box  the  scales  are  placed  and  the  water  is  kept  in 
constant  circulation  by  means  of  small  agitators  electrically 


234    EVOLUTION   OF   WEIGHTS   AND   MEASURES 

driven  and  in  motion  except  at  the  moment  of  reading.  A 
number  of  thermometers  arranged  in  close  proximity  to  the  scales 
enable  a  series  of  accurate  readings  of  the  temperature  to  be  made 
with  microscopes  placed  above  for  that  purpose.  It  will  readily 
be  seen  that  by  changing  the  temperature  of  the  surrounding 
water,  the  amount  of  expansion  of  a  scale  can  be  measured.1 

Improvements  have  been  made  in  the  micrometer-microscope 
as  well  as  in  the  rest  of  the  apparatus,  and  particularly  in  the 
screws  which  form  the  basis  for  moving  the  cross-hairs  and 
for  measuring  the  amount  of  motion.  These  improvements 
consist  essentially  of  a  frame  carrying  several  sets  of  cross-wires 
in  pairs,  which  occupy  a  vertical  position  in  the  field  of  view 
of  the  microscope.  This  frame  is  set  at  the  focal  plane  of 
the  objective,  and  can  be  moved  laterally  by  means  of  a  screw 
with  a  graduated  head  and  handle.  Such  screws  are  so  con- 
structed that  they  are  practically  free  from  constant  or  periodic 
-error,  and  by  means  of  a  spring,  any  "  back-lash  "  or  lost  motion 
between  the  screw  and  nut  is  guarded  against.  The  head  of 
the  screw  is  graduated  to  a  certain  number  of  divisions,  usually 
100,  so  that  a  fractional  part  of  the  revolution  of  the  screw 
can  be  determined  accurately.  For  example,  if  a  pair  of  cross- 
wires  are  focussed  over  a  line  of  a  scale,  it  is  possible,  by  noting 
the  number  of  revolutions  of  the  screw,  to  bring  those  cross- 
wires  over  the  next  line,  to  determine  the  value  of  a  single 
revolution  of  the  screw,  and  by  means  of  its  divided  head  and  a 
vernier,  of  minute  fractions  of  a  single  revolution.  Where  cross- 
wires  of  the  ordinary  or  X  type  were  once  employed  and  a  setting 
made  on  the  centre  of  the  magnified  division,  it  is  now  usual  to 
employ  two  vertical  cross- wires,  following  a  plan  proposed  by 
Kupffer  when  preparing  the  Eussian  standards,  and  to  arrange 
the  setting  with  respect  to  the  edges  of  the  engraved  line.  This 
lends  itself  to  greater  accuracy,  as  by  means  of  the  bright  borders 
of  the  image  of  the  line  a  much  sharper  setting  can  be  made 
than  where  the  magnified  line  was  bisected  by  a  single  cross- 
wire.  The  magnifying  power  of  the  microscope  for  accurate 
comparisons  ranges  from  80  to  250  times,  and  in  some  few  rare 
cases  even  higher,  the  most  serviceable  power  being  determined 

1A  description  of  the  Brunner  Comparator  of  the  International  Bureau  will  be 
found  in  Travaux  et  Mdmoires  du  Bureau  International  des  Poids  et  Mesures,  vol .  4. 


STANDARDS   AND   COMPARISON  235 

after  considering  the  conditions,  as,  under  many  circumstances, 
increased  magnification  introduces  errors  and  does  not  result 
in  as  satisfactory  results  as  with  the  use  of  a  lower  power.1 

There  must  also  be  considered  the  illumination  of  the  face  of 
the  rule,  and  it  is  now  usual  to  provide  direct  illumination,  rather 
than  oblique.  This  is  accomplished  by  the  use  of  a  prism  which 
will  reflect  light  from  a  distant  source,  such  as  an  incandescent 
lamp  with  a  ground  glass  globe,  to  the  scale  and  then  to  the 
objective  of  the  microscope.  A  transparent  plate  of  plane  glass 
placed  in  the  tube  of  the  microscope  at  an  angle  of  45  degrees  to 
the  axis,  will  also  produce  the  same  result,  and  is  preferred  by 
some  observers. 

As  regards  the  manner  in  which  the  adjustment  of  the  scale  is 
accomplished,  two  main  divisions  of  comparators  can  be  made, — 
those  which  give  the  transverse  movement  of  the  scales,  and  those 
in  which  the  scales  are  moved  longitudinally.  A  longitudinal 
comparator  is  so  arranged  that  the  divisions  of  a  standard  can  be 
studied  accurately ;  for  example,  throughout  the  entire  length ;  or 
standards  of  different  lengths,  whose  differences  exceed  the 
diameter  of  the  field  of  the  microscopes,  can  be  measured  with 
facility.  Thus  from  a  standard  meter,  a  bar  or  tape  of  several 
times  this  length  for  use  in  measuring  a  base  line  or  in  surveying, 
can  be  standardized.  In  a  comparator  of  this  kind  the  scales 
must  be  so  adjusted  that  they  lie  with  their  axis  either  in  a 
perfectly  straight  line  or  exactly  parallel. 

In  the  comparators  where  the  scales  have  a  transverse  move- 
ment, as  is  the  case  with  an  instrument  designed  for  comparing 
two  scales  of  the  same  length,  the  microscopes  are  mounted  at  a 
fixed  distance,  and  the  scales  are  adjusted  so  that  their  axes  are 
parallel  to  a  line  connecting  the  two  microscopes.  The  two 
scales  should  rest  in  a  carriage  protected  from  changes  of 
temperature  by  means  already  described,  and  so  arranged  that 
after  being  adjusted  parallel  to  each  other,  they  can  be  moved 
under  the  two  microscopes.  Such  an  arrangement  enables  one  to 
study  the  relative  expansion  of  scales  of  different  materials,  as  the 
measurement  of  the  differences  of  length  at  a  certain  temperature 

JSee  W.  A.  Rogers,  "On  the  Present  State  of  the  Question  of  Standards  of 
Length,"  Proceedings  American  Academy  of  Arts  and  Sciences,  vol.  xv.  1879-80, 
pp.  290-291. 


236    EVOLUTION   OF   WEIGHTS   AND   MEASURES 

can  be  made,  and  then,  at  a  second  temperature,  obtained  by 
varying  the  warmth  of  the  circulating  water. 

With  standards  of  mass,  the  material  of  which  they  are  com- 
posed is  of  primary  importance.  Not  only  must  the  standard  be 
of  a  permanent  character,  hard  and  able  to  resist  abrasion  in  actual 
use,  but  it  must  be  such  that  it  will  not  be  affected  by  the  oxygen 
of  the  air,  or,  in  other  words,  have  its  surface  oxidized  and  the 
weight  increased.  Other  and  more  subtle  chemical  changes  must 
also  be  provided  against.  On  this  account,  platinum  and  rock 
crystal  have  been  found  to  be  the  most  useful  materials,  and  the 
former  posesses  the  merit  of  having  a  high  specific  gravity,  so 
that  when  weighed  in  air  the  amount  displaced  is  a  minimum. 
Furthermore,  the  shape  must  be  such  that  the  volume  can  be 
measured  with  a  high  degree  of  exactitude,  as  on  the  volume 
depends  the  effect  of  buoyancy,  and  of  temperature.  Such  cor- 
rections are  often  very  small ;  in  fact,  much  less  than  in  the 
case  of  a  standard  of  length,  but  in  constructing  and  using  a 
standard  of  mass,  the  barometric  pressure,  temperature,  and  the 
humidity  should  be  determined,  as  the  density  of  the  air  must 
be  known  accurately  and  duly  considered. 

In  addition  to  possessing  a  geometrical  figure  easily  measured^ 
the  standard  should  be  so  designed  that  there  are  no  grooves  or 
cavities  to  collect  dust,  and  that  when  used  in  a  balance  it  will 
conform  to  the  needs  of  the  mechanism  used  for  changing  the 
weights  in  the  scale-pans.  Taking  all  things  into  considera- 
tion, the  cylindrical  shape  with  round  edges  serves  the  best, 
and  such  is  the  form  of  the  Kilogram  of  the  Archives  and  of 
the  International  Prototype  and  its  copies. 

For  determining  standards  of  mass,  the  modern  physicist 
has  recourse  to  the  same  instrument  which  was  employed  thou- 
sands of  years  ago  by  the  ancients,  viz.  the  balance  with  equal 
arms.  But  he  has  effected  such  improvements  in  its  mechanical 
construction  and  operation  that  this  instrument  is  now  entitled  to 
rank  with  the  apparatus  of  precision  of  the  first  order.  For 
accurate  weighing,  the  balance  must  be  of  the  finest  and  most 
accurate  workmanship,  and  also  there  must  be  employed  various 
methods  and  corrections  evolved  largely  from  mathematical 
considerations. 

In  comparing  standards  of  mass,  and  in  all  accurate  weighings* 


STANDARDS   AND   COMPARISON  237 

with  a  balance,  it  is  necessary  to  take  into  consideration  the 
buoyant  effect  of  the  displaced  air,  as  conditions  are  quite 
different  from  those  obtained  when  a  body  is  weighed  in  a 
vacuum.  This  correction  is  especially  necessary  in  making  an 
absolute  determination,  but  in  cases  where  the  standard  and 
the  weights  with  which  it  is  compared  are  of  the  same  material, 
the  effect  is  the  same  in  both  cases  and  does  not  enter  into 
consideration  at  all. 

For  accurate  weighing  it  is  possible  to  employ  the  method 
of  double  weighing  of  Borda,  where  the  two  objects  whose  masses 
are  to  be  compared  are  successively  placed  in  the  same  scale- 
pan  and  are  counterpoised  by  weights  on  the  opposite  side,  or 
the  interchange  of  the  weights  on  the  scale-pans,  as  devised  by 
Gauss.  There  must  be  considered,  also,  the  effect  of  temperature, 
which  can  change  the  condition  of  balances  and  weights,  just  as 
much  as  in  other  physical  operations,  and  it  is  accordingly 
necessary  to  have  such  a  balance  placed  in  a  room  with  constant 
temperature,  and  to  provide  against  currents  of  air,  by  means  of  a 
suitable  case.  Even  the  influence  of  the  temperature  of  the 
observer's  body  has  its  effect,  and  he  must  be  placed  as  far  as 
possible  from  the  balance,  observing  the  oscillation  of  the  beam 
with  a  small  telescope,  and  changing  the  weights,  setting  the 
beam  in  motion  and  bringing  it  to  rest,  and  performing  other 
necessary  operations  by  suitable  mechanical  devices,  which  can 
be  operated  at  a  distance,  without  opening  the  casing  of  the 
balance. 

These  conditions  are  realized  in  the  balances  used  at  the 
Bureau  International,  as  well  as  at  various  governmental 
Bureaus  of  Standards,  physical  laboratories  and  like  institutions. 
Typical,  perhaps,  as  involving  the  greatest  refinements,  are  the 
balances  of  the  Bureau  International,  two  forms  of  which  are 
described  in  outline  below. 

Of  these  perhaps  the  simplest  is  the  Euprecht  type  of  balance, 
which  consists  of  a  balance  with  equal  arms  carrying  two  scale- 
pans  in  which  an  opening  is  cut  in  the  form  of  a  cross,  the  edge 
being  cut  away  at  one  of  the  branches.  Beneath  this  is  an  axis 
carrying  a  cross-shaped  piece  of  somewhat  smaller  dimensions 
than  the  opening  in  the  scale-pan.  Two  supports  similar  in 
shape  to  the  scale-pans  and  provided  with  like  openings  are 


238    EVOLUTION   OF   WEIGHTS   AND   MEASURES 

attached  to  the  central  column  supporting  the  balance.  When 
a  weight  is  placed  on  the  scale-pan  by  means  of  mechanism 
operated  from  a  distance  of  over  four  meters,  it  is  possible  for  the 
cross-shaped  piece  below  to  be  raised,  thus  carrying  the  weight 
clear  of  the  scale-pan,  and  then  to  be  swung  out  through  the 
opening  clear  of  the  latter,  and  into  the  plate  placed  on  the 
central  column  where  the  weight  may  be  deposited.  The 
standard  carrying  the  cross-shaped  piece  is  then  lowered 
and  the  weight  is  left  on  the  rest.  The  weights  can  then  be 
revolved  around  the  central  column  carrying  the  beam  and  by  the 
apparatus  just  mentioned  placed  on  opposite  pans  from  their 
original  position.  This  operation  is  accomplished  by  means  of 
gears  and  shafts,  and  is  carried  on  simultaneously  for  both  pans 
of  the  balance.  Mechanism  is  also  provided,  so  that  the  observer 
may  release  the  pans  and  also  the  beam,  by  turning  suitable 
cranks,  and  there  is  a  telescope,  whereby  he  may  observe  the 
deflections  of  the  beam  by  means  of  a  mirror  and  divided  scale.1 

The  Bunge  balance,  at  the  Bureau  International  des  Poids  et 
Mesures,  contains  several  features  leading  to  further  refinements. 
It  is  enclosed  in  a  copper  case,  from  which  the  air  may  be 
exhausted,  so  that  the  weights  may  be  compared  in  vacuo.  In 
addition  to  the  means  of  changing  the  weights,  and  for  releasing 
and  arresting  the  scale-pans  and  beam,  mechanism  is  provided 
whereby  small  additional  weights  can  be  added  to  one  side  or  the 
other  of  the  beam,  as  is  found  necessary.  All  of  the  controlling 
devices  are  so  arranged  that  they  may  be  operated  by  the 
observer  from  a  distance  of  several  meters,  and  with  this  balance 
the  most  accurate  results  may  be  obtained. 

In  the  determination  of  standards  of  mass,  it  is  necessary  to 
determine  their  specific  gravity  and  the  amount  of  water  that 
they  displace  when  immersed.  For  this  hydrostatic  balances 
are  used,  which,  in  their  essential  features,  correspond  with  the 
balances  of  precision  just  described.  The  vessel  containing  the 
water  in  which  the  weight  is  immersed  is  placed  directly  below 

1  Guillaume's  La  Convention  du  Metre,  p.  111.  The  balances  have  been  pro- 
vided with  suitable  mechanism  to  add  small  differential  weights,  i.e.  at  the  same 
time  two  weights  say  of  100  and  100*5  milligrams  respectively,  which  give  a  new 
position  of  equilibrium  and  allow  the  determination  of  the  sensitiveness.  This 
addition  of  small  weights  can  be  made  without  arresting  the  balance  which  con- 
stitutes a  great  saving  of  time. — Ch.  Ed.  Guillaume. 


STANDARDS   AND   COMPARISON 

the  point  of  support  of  one  of  the  arms  of  the  balance.  There 
is  also  provided  a  scale-pan,  in  which  the  body  to  be  measured 
is  placed,  and  connected  with  it — a  device  by  which  it  can  be 
supported  when  immersed  in  water — the  whole  forming  "a  con- 
tinuous arrangement  supported  from  one  arm.  The  body  is  first 
placed  in  the  upper  pan  and  counterbalanced  by  weights  on  the 
opposite  side  of  the  balance.  It  is  then  removed  and  weights 
are  added  in  its  place  until  the  equilibrium  of  the  balance  is 
secured.  The  sum  of  the  weights  so  added  gives,  of  course,  the 
actual  weight  of  the  body.  It  is  then  immersed  in  water,  and 
the  same  process  is  gone  through  with,  the  temperature  of  the 
water  being  noted  by  a  carefully  calibrated  thermometer.  Various 
devices  are  employed  to  secure  a  uniform  temperature  of  the 
water,  to  diminish  the  effects  of  friction  and  capillarity,  and  to 
facilitate  the  handling  of  the  body  when  immersed. 

The  sensibility  of  an  accurate  balance  depends  on  the  load,, 
and  in  making  a  weighing,  this  factor  must  be  determined 
accurately,  and  it  is  likely  to  vary  under  different  conditions. 
With  the  balances  employed  in  comparing  the  standard  kilo- 
grams, it  is  usual  to  have  the  sensibility  equal  to  25  to  50 
divisions  for  a  milligram,  or,  in  other  words,  an  addition  of 
weight  equal  to  a  milligram  produces  a  deflection  of  the  beam 
corresponding  to  this  amount.  This  is  useful,  inasmuch  as  the 
differences  of  weight  between  the  two  standards  compared  are 
usually  so  small  as  to  be  measured  only  by  the  deflection,  and  not 
requiring  the  addition  of  the  smaller  weights  to  either  scale-pan. 

In  some  cases,  a  reading  of  a  tenth  of  a  division  of  the 
deflection  in  either  direction  may  correspond  to  some  thousandths 
of  a  milligram.  Thus,  in  comparisons  of  standard  kilograms,  the 
•01  of  a  milligram  would  be  equal  to  a  '000,000,01  of  the  mass 
measured,  but  other  considerations  do  not  permit  this  degree  of 
precision  to  be  maintained.  Nevertheless,  this  represents  a 
substantial  gain  in  accuracy,  as  the  fine  balance  used  at  the 
London  Mint  by  Harris  in  1743  was  able  to  indicate  only  -J-  of 
a  grain  on  a  Troy  pound,  or  about  one  part  in  50,000,  while  in 
adjusting  the  Kilogram  of  the  Archives  in  1779,  Fortin  employed 
a  balance  sensitive  to  one  part  in  a  million. 

As  units  of  capacity  are  defined  in  terms  either  of  linear 
measures  or  of  mass,  the  construction  of  suitable  standards  does 


240    EVOLUTION   OF   WEIGHTS   AND   MEASURES 

not  present  any  particular  difficulty,  nor  is  any  high  degree  of 
precision  required,  save  in  a  few  cases.  In  fact,  standard 
measures  of  capacity  are  usually  adjusted  by  means  of  the 
weight  of  a  liquid  such  as  water,  taken  at  a  certain  temperature. 
As  these  measures  are  used  in  few  experiments  or  determina- 
tions where  extreme  accuracy  is  called  for,  there  is  no  need 
of  observing  particular  precautions,  either  in  their  construction 
or  their  calibration.  The  standards  are  usually  of  some  metal, 
such  as  bronze  or  gun-metal,  of  a  regular  geometrical  shape, 
and  are  adjusted  with  water  at  a  certain  temperature.  The 
purpose  for  which  a  measure  of  capacity  is  to  be  used  is  borne 
in  mind  in  determining  its  shape,  as  with  liquids  it  is  not 
necessary  to  take  into  consideration  the  question  of  compres- 
sibility or  of  heaping  the  measure  which  would  be  involved  in 
the  measurement  of  grain  or  vegetables.  This,  of  course,  does 
not  affect  the  actual  cubical  contents  of  the  measure,  but  merely 
-considers  its  actual  application  in  commerce.  Thus,  in  Great 
Britain  there  have  been  various  shapes  adopted  for  standards  for 
the  liquid  and  dry  gallon,  and  for  the  coal  bushel,  and  for  other 
measures,  the  exact  dimensions  of  which  are  defined.  In  view 
of  the  great  inaccuracy  in  measuring  goods  by  capacity  measures 
being  unavoidable,  it  is  the  present  tendency  of  metrology  to 
•use  capacity  measures  as  little  as  possible,  and  to  recommend 
the  use  of  weights,  especially  in  business  dealings.  In  Europe 
this  practice  is  rapidly  increasing  among  the  metric  countries, 
3,nd  in  some  of  them  nearly  all  articles  of  food  and  other 
necessities  for  daily  life,  even  liquids  such  as  oil,  are  bought  and 
sold  by  weight. 

There  is,  however,  one  kind  of  standard  of  capacity  where 
accuracy  is  important,  namely,  flasks,  burettes,  or  other  vessels  of 
glass  employed  in  physical  or  chemical  experiments.  These  are 
calibrated  carefully  with  water  or  mercury,  whose  volume  at  any 
specified  temperature  is  known  with  exactness.  Such  standards, 
however,  are  not  specially  and  exclusively  maintained  by  national 
bureaus  and  direct  comparisons  made  with  them,  but  as  their  cali- 
bration involves  little  difficulty  to  the  trained  physicist  or  chemist,1 

1  The  calibration  of  chemical  and  other  graduated  glass-ware  is  one  of  the 
regular  routine  duties  of  the  National  Bureau  of  Standards  at  Washington,  and 
is  done  for  the  technical  public  at  reasonable  and  established  fees. 


STANDARDS   AND   COMPARISON  241 

they  are  usually  constructed  in  any  laboratory  where  their  use 
is  desired. 

In  the  case  of  other  standards,  such  as  those  of  electricity,  the 
most  important  are  the  ohm  and  the  standard  cell,  which  involve 
the  realization  of  the  international  definitions1  by  careful  scientific 
work.  These  definitions  for  practical  purposes  are  so  exact  and 
the  modes  of  construction  so  well  understood  by  physicists  that 
such  standards  can  be  constructed  at  national  or  other  physical 
laboratories  and  bureaus  of  standards  by  trained  investigators, 
and  the  results  represent  refined  methods  of  manipulation  and  the 
use  of  specific  apparatus  rather  than  scientific  work  of  such 
character  as  was  involved  in  the  construction  of  the  international 
standards  of  length  and  mass.  It  should  not  be  understood, 
however,  that  from  the  purely  scientific  point  of  view  that 
electrical  engineers  and  physicists  are  altogether  satisfied  with 
the  present  definitions.  Consequently  there  is  at  present  much 
important  investigation  in  progress  which  has  as  its  object  the 
determination  of  new  standards  or  new  definitions,  and  at  the 
Electrical  Congress  held  at  St.  Louis  in  1904  it  was  decided  that 
steps  should  be  taken  to  form  an  international  electrical  com- 
mission composed  of  official  representatives,  much  after  the  fashion 
of  the  International  Commission  of  Weights  and  Measures.  The 
call  for  a  preliminary  meeting  of  delegates  has  been  issued  and 
the  formation  of  this  international  commission  in  the  near  future 
is  probable.  From  the  discussion  of  the  electrical  units  in  the  last 
chapter  their  independence  on  each  other  will  be  appreciated,  so 
that  it  is  necessary  to  determine  whether  the  voltameter  operating 
under  standard  conditions  shall  give  the  unit  of  current  from 
which,  with  the  ohm,  may  be  derived  the  unit  of  electromotive 
force,  or  whether  the  unit  of  electromotive  force  as  given  by  a 
standard  cell  shall  be  considered  the  fundamental  source  of  the 
standards. 

There  have  been  constructed  by  the  Physikalisch-Technische 
Keichsanstalt  at  Berlin  and  the  English  National  Physical 
Laboratory,  primary  mercurial  standards  of  resistance  in  which 
the  international  definition  of  the  ohm  has  been  realized  and 
the  apparatus  of  these  two  laboratories  shows  substantial 
agreement  of  measurement,  being  in  harmony  to  a  few  parts  in 

1  See  chapter  ix.  ante. 
Q 


242    EVOLUTION   OF   WEIGHTS   AND   MEASURES 

lOOjOOO.1  Furthermore  there  are  in  England,  preserved  at  the 
Board  of  Trade  Electrical  Standardizing  Laboratory  in  London, 
actual  standards  of  resistance,  current  and  electrical  pressure 
which  have  been  duly  legalized  (Order  in  Council,  August  23, 1894). 
Thus  the  standard  ohm  is  the  resistance  between  the  copper  ter- 
minals of  the  platinum-silver  coil  marked  "  Board  of  Trade  Ohm 
Standard,  verified  1894,"  to  the  passage  of  an  unvarying  electrical 
current,  when  the  coil  of  insulated  wire  forming  part  of  the 
aforesaid  instrument  and  connected  to  the  aforesaid  terminals  is 
in  all  parts  at  a  temperature  of  15'4  degrees  Centigrade. 

The  standard  ampere  is  the  current  which  passes  in  and  through 
the  coils  of  wire  of  the  standard  ampere  balance,  marked  "  Board 
of  Trade  Ampere  Standard,  verified  1894,"  when  on  reversing  the 
current  in  the  fixed  coils  the  change  in  the  forces  acting  upon 
the  suspended  coil  in  its  sighted  position  is  exactly  balanced  by 
the  force  exerted  by  gravity  in  Westminster  upon  the  iridio- 
platinum  weight  marked  "  A"  and  forming  part  of  said  instrument. 

The  British  standard  volt  is  one-hundredth  part  of  the  pressure 
which,  when  applied  between  the  terminals  of  a  Kelvin  electro- 
static voltmeter  of  the  multicellular  type  marked  "  Board  of  Trade 
Standard,  verified  1894,"  causes  a  certain  exactly  specified  amount 
of  rotation  of  the  suspended  part  of  the  instrument. 

While  various  other  standards  are  of  course  possessed  by  the 
different  national  laboratories  and  testing  bureaus,  yet  they  aim 
rather  at  representing  specifically  the  definitions  of  the  various 
units,  than,  as  in  the  case  of  the  British  Board  of  Trade,  employing 
as  national  standards  the  mere  concrete  apparatus.  The  same 
holds  true  for  standard  barometers,  thermometers,  polariscopes, 
and  other  instruments  of  precision  which  are  used  for  standardizing 
similar  instruments  used  in  science  and  industry. 

Having  considered  the  general  principles  underlying  standards 
and  their  construction  and  comparison,  it  may  be  advantageous  to 
discuss  briefly  the  weights  and  measures  that  have  served  this 
purpose  in  France  and  England,  as  well  as  the  present  metric 
standards.  While  it  was  legally  possible  to  establish  the  inch  by 
taking  "  three  barley  corns  round  and  dry  "  as  was  provided  by 
the  statute  of  Edward  II.  and  to  raise  a  pound  from  7680  grains 

lrThe  first  standard   ohm   was  constructed   privately   by   M.    Benoit   of   the 
Bureau  International. 


STANDARDS   AND   COMPARISON  243 

of  wheat  as  was  enacted  by  the  statute  of  the  Assize  of  Bread  and 
Ale  (51  Henry  III.,  stat.  1,  1266),  yet  such  means  on  their  very 
face  were  manifestly  lacking  in  accuracy,  as  there  was  nothing  to 
ensure  that  the  corns  or  grains  would  conform  to  a  uniform 
standard.  Consequently  as  early  as  the  fourteenth  year  of  the 
reign  of  Edward  III.  (1340)  a  royal  edict  was  published  ordering 
"  standard  weights  and  measures  to  be  made  of  brass,  and  sent 
into  every  city  and  town  in  the  kingdom."  This  necessary  and 
excellent  law,  however,  merely  followed  the  precedent  made  by 
Eichard  I.:  who  ordered  that  standard  measures  of  length  should 
be  made  of  iron  and  that  those  for  capacity  should  have  iron 
brims,  and  that  standard  measures  of  every  kind  should  be  kept 
by  the  sheriffs  and  magistrates  of  towns.  While  it  cannot  be 
said  that  this  law  was  enforced,  yet  it  shows  that  the  government 
was  alive  to  the  necessity  of  proper  standards  in  order  to 
secure  the  desired  uniformity  and  that  their  construction  was 
constantly  in  mind. 

The  earliest  English  standard  of  length  extant  is  the  Exchequer 
standard  yard  of  Henry  VII.,  which  dates  back  to  1496.  It  is  a 
brass  bar  of  octagonal  cross  section  whose  length  furnished  the 
standard  distance,  and  which  is  divided  both  into  inches  and  also 
into  sixteen  equal  parts  on  the  basis  of  binary  division.  It  was 
used  until  1588,  when  in  the  reign  of  Queen  Elizabeth  a  new 
standard  yard,  also  of  brass,  was  constructed,  which  is  still  in 
existence  after  having  served  for  a  long  period  as  an  original 
standard.  It  is  a  rectangular  bar  one  yard  in  length,  on  which 
are  indicated  the  divisions  of  a  yard  and  also  a  similar  bar  forming 
an  ell  of  45  inches  (exact  length  45'04  inches),  there  being  a 
third  and  larger  bar  with  two  beds  or  matrixes  into  which  both 
of  the  end  standard  bars  could  fit,  and  having  at  one  end  of  the 
yard  bed  a  subdivision  into  inches  and  half  inches.  It  may  be 
said  in  passing  that  both  the  standards  of  Henry  VII.  and  of 
Elizabeth  are  essentially  of  the  same  length,  and  they  are  only 
about  *01  inch  shorter  than  the  present  British  imperial  standard. 
The  Elizabethan  standard  did  duty  until  well  into  the  nineteenth 
century,  in  spite  of  the  fact  that  some  time  between  1760  and 
1819  it  had  been  broken  and  mended  by  means  of  a  dovetail 
joint  in  a  rather  crude  fashion.  In  fact  this  ancient  standard  has 
been  spoken  of  most  contemptuously  by  F.  Baily,  who  examined 


244    EVOLUTION   OF   WEIGHTS   AND   MEASURES 

it  in  1836,  he  even  going  as  far  as  to  call  it  disgraceful  for  the 
British  government  to  issue  certificates  and  construct  copies 
based  on  it  as  representing  the  English  standard.1 

A  line  standard  constructed  by  Bird  in  1760,  under  the 
authorization  of  the  Committee  on  Weights  and  Measures  of 
the  House  of  Commons,  was  based  upon  a  standard  made  by 
the  same  maker  in  1742  for  the  Eoyal  Society,  and  on  a  line 
standard  which  he  constructed  in  1758.  The  former  has  been 
pronounced  by  H.  W.  Chisholm,  an  authority  on  British 
metrology,  to  be  "  the  first  scientifically  constructed  measure 
of  length  in  this  country"  (England).2  The  Bird  standard  of 
1760  was  approved  by  the  Committee,  and,  though  not  at  that 
time  legally  established,  formed  a  basis  for  a  number  of 
secondary  standards.  It  was  eventually  adopted  as  the  legal 
standard  of  Great  Britain  by  an  Act  of  Parliament  promulgated 
June  17,  1824,  and  served  as  such  until  its  destruction  in  the  fire 
which  consumed  the  Houses  of  Parliament  in  1834.  The  adop- 
tion of  this  standard,  however,  at  this  time  was  hardly  warranted 
in  view  of  the  state  of  scientific  knowledge,  or  by  the  actual 
character  of  the  standard  itself.  It  was  a  brass  bar,  1'05  inch 
square  and  3973  inches  in  length,  with  gold  plugs  near  the  ends, 
on  which  were  points  or  dots,  the  distance  between  which  at  the 
temperature  of  62  degrees  Fahrenheit  (16'7  degrees  Centigrade) 
represented  the  standard  yard.  This  standard  bar,  however,  in 
addition  to  being  of  comparatively  crude  construction,  even  at 
the  time  of  its  legal  adoption  had  become  badly  worn  by  rough 
treatment.  By  the  use  of  beam-compasses,  and  in  various  rough 
comparisons,  the  dots  had  become  worn,  so  that  under  the  micro- 
scope they  were  seen  to  appear  like  the  craters  of  small  volcanoes, 
and  consequently  rendered  the  bar  quite  unsuitable  for  exact 
scientific  work.  In  the  Act  by  which  this  standard  was  estab- 
lished it  is  clear  that  the  idea  of  a  natural  standard  was  still 
cherished,  since  it  provided  that  in  the  event  of  the  loss  of 
the  standard  yard  it  should  be  restored  by  means  of  a  reference 

1  See  H.  W.  Chisholm,  "Seventh  Annual  Report  of  the  Warden  of  the  Standards," 
1872-3,   English  Parliamentary  Papers,  Reports  from  Commissioners,  1873,  vol. 
xxxviii.  pp.  25  and  34;  also  id.  "Weighing  and  Measuring"  (London,  1877),  pp. 
50-54.     See  also  footnote,  p.  36,  ante. 

2  See  Chisholm  in  same  Report,  p.   10,  for  full  description  of  this  and  other 
standards. 


STANDARDS   AND   COMPARISON 


245 


to  a  pendulum  beating  seconds  in  a 
vacuum,  at  the  latitude  of  London 
and  reduced  to  sea  level,  which  would 
have  the  relation  to  the  yard  of 
39-1393  to  36  ;  but  in  spite  of  this 
statutory  provision,  when  the  standard 
yard  was  destroyed  ten  years  later  no 
recourse  was  had  to  the  seconds' 
pendulum,  as  that  method  seemed  then 
incapable  of  furnishing  the  standard 
with  sufficient  exactness,  and  the  stan- 
dard yard  was  reconstructed  from  other 
standards  in  the  possession  of  the 
Government  and  scientific  societies 
which  had  been  compared  with  the 
standard  of  1760.  These  included  the 
five-foot  brass  standard  scale  of  Sir 
George  Shuckburgh  which  was  made 
by  Troughton,  of  London,  in  1796,  two 
iron  standards  made  for  the  Ordnance 
Survey  in  1826-7,  the  brass  tubular  scale 
of  the  Eoyal  Astronomical  Society,  and 
the  standard  yard  of  the  Koyal  Society 
constructed  under  Captain  Kater's 
direction  in  1831.  The  Shuckburgh 
scale  was  based  on  a  five-foot  scale 
made  and  used  by  Troughton,  which  in 
turn  was  constructed  from  an  accurate 
90-inch  brass  scale  made  by  Bird.1 

This  imperial  standard  yard,  as  well 
as  the  imperial  standard  prepared 
under  the  direction  of  a  Parliamentary 
Committee  appointed  in  1843,  were 


BRITISH  IMPERIAL  YARD. 


W.  Harkness,  "Progress  of  Science  as 
Exemplified  in  the  Art  of  Weighing  and 
Measuring,"  Bulletin,  Philosophical  Society  of 
Washington,  D.C.,  vol.  x.  ;  Smithsonian  Miscell- 

aneous Collection,  vol.  xxxiii.  1888,  pp.  43  et  seq.  Also  W.  A.  Rogers,  "On  the 
Present  State  of  the  Question  of  Standards  of  Length,"  Proceedings,  American 
Academy  of  Arts  and  Sciences,  vol.  xv.  1879-80,  pp.  273  et  seq. 


246    EVOLUTION   OF   WEIGHTS   AND   MEASURES 

duly  legalized  in  1855  (18  and  19  Viet.  c.  72)  by  an  Act 
known  as  the  Standards  Acts,  whose  provisions  as  regards 
these  standards  were  re-enacted  in  the  Weights  and  Measures 


O 


BRITISH  IMPERIAL  STANDARD  YARD.     Cross-section.    (Exact  size.) 
1. — Section  of  Bar.  2. — Section  through  holes. 

Act  of  1878.  These  standards,  as  they  represent  the  best 
practice  of  the  time  of  their  construction,  and  as  they  are 
the  present  standards  of  Great  Britain,  may  be  briefly  de- 
scribed.1 The  imperial  standard  yard  is  a  solid  square  bar 
of  a  special  bronze  or  gun-metal  known  as  Baily's  metal, 
composed  of  copper  16  parts  by  weight,  tin  2J,  and  zinc  1. 


DIAGRAM  SHOWING  BRITISH  IMPERIAL  STANDARD  YARD  FROM  ABOVE,     a— a  =  lyard. 

It  is  38  inches  in  length,  with  a  cross  section  one  inch  square, 
and  has  near  its  ends  two  circular  holes  or  wells  sunk  to  a 
point  midway  the  depth  of  the  bar.  In  these  wells  are  inserted 
two  gold  studs,  on  which  the  fiducial  lines  are  engraved,  the 
distance  between  them  forming  the  imperial  standard  yard  of  36 
inches  at  a  temperature  of  62  degrees  Fahrenheit  (16|°  C.).  This 
imperial  standard,  as  also  the  imperial  standard  pound,  is  pre- 
served in  a  strong  fire-proof  room  at  the  Standards  Office  in 
Old  Palace  Yard,  Westminster,  and  copies  are  deposited  at 

1G.  Airy,  "Account  of  the  Construction  of  the  New  National  Standards  of 
Length,  and  of  its  Principal  Copies,"  Philosophical  Transactions  (London),  18th 
June,  1857. 


STANDARDS   AND   COMPARISON  247 

the  Royal  Observatory,  Greenwich,  the  Royal  Mint,  the  Royal 
Society,  and  the  Houses  of  Parliament.  The  latter  are  specially 
designated  by  statute  as  Parliamentary  copies,  and  must  be  com- 
pared with  the  imperial  standard  once  in  every  ten  years,  since 
in  the  event  of  the  possible  destruction  of  the  latter  they  would 
furnish  the  source  from  which  a  new  standard  would  be  derived. 
There  were  in  addition  thirty-five  other  standards  made  of  the 
same  size  and  of  the  same  material,  which  were  duly  compared 
with  the  prototype,  and  were  distributed  to  the  various  nations  of 
the  world  and  to  scientific  institutions  in  Great  Britain  and  else- 
where. One  of  these  standard  bars,  by  Act  of  Parliament,  June 
30,  1855,  was  presented  to  the  United  States  Government,  and 
was  known  as  "Bronze  Standard  No.  11."  It  is  '000088  inch 
shorter  than  Bronze  Standard  No.  1,  which  was  chosen  as  the 
imperial  standard.  It  was  accompanied  by  a  malleable  (Low 
Moor)  iron  standard  of  length,  No.  57,  and  standard  weight  No.  5, 
the  correction  for  each  standard  being  given  over  the  signature  of 
'G.  B.  Airy,  Astronomer-Royal.1 

These  two  yards,  particularly  the  bronze  standard,  were  so 
much  superior  to  the  Troughton  scale  that  they  were  accepted 
by  the  United  States  Office  of  Weights  and  Measures  as  the 
standards  of  the  United  States,  and  in  this  way  comparisons 
of  American  measures  of  length  were  made  with  the  imperial 
yard.  In  1876,  and  again  in  1888,  they  were  taken  to  England 
and  were  compared  with  the  British  standards. 

In  1904,  the  late  H.  J.  Chany,  Warden  of  the  Standards,  caused 
to  be  constructed  and  standardized  at  the  International  Bureau  a 
platinum-iridium  bar  similar  in  composition  and  section  to  the  inter- 
national meter,  and  while  this  has  not  as  yet  any  legal  standing, 
it  is  perhaps  the  best  representative  of  the  British  yard. 

The  oldest  authenticated  British  standards  of  weight  date  from 
the  reign  of  Queen  Elizabeth,  and  consist  of  three  distinct  sets. 
The  first  of  these  are  bell-shaped  standards  of  bronze  for  the 
heavier  weights,  and  range  from  56  Ibs.  to  1  Ib.  inclusive.  They 
are  of  importance,  as  from  the  time  of  their  construction  in  1588 
until  1824  they  were  the  standards  of  the  kingdom.  Then  there 

1  See  Report,  Superintendent  U.S.  Coast  and  Geodetic  Survey,  1877,  Appendix 
12,  p.  154,  for  description  of  these  standards  of  length.  See  also  Executive 
Document  27,  34th  Congress,  3rd  Session,  p.  17. 


248    EVOLUTION   OF   WEIGHTS   AND   MEASURES 


is  a  series  of  flat  circular  avoirdupois  weights  from  8  Ibs.  to  ^ 
of  an  ounce,  and  a  set  of  cup-shaped  Troy  weights  which,  with  the 
exception  of  the  very  small  weights,  fitted  into  each  other.  These 
standards  had  been  prepared  under  the  direction  of  a  committee 
of  merchants  and  goldsmiths,  who  employed  as  the  basis  for 
avoirdupois  weight  a  56  Ib.  standard  of  the  Exchequer  dating  from 
Edward  III.,  and  for  Troy  weight  the 
ancient  standard  of  the  Goldsmiths'  Hall. 

About  1758  the  Parliamentary  Com- 
mittee, to  which  we  have  before  referred, 
caused  to  be  constructed  three  standard 
Troy  pound  weights,  but  like  the  yard  of 
the  same  period  none  of  these  was  legalized 
until  1824,  when  one  of  the  weights  was 
chosen  as  the  government  standard,  only 
to  be  destroyed  by  the  fire  of  ten  years 
later.  On  the  recommendation  of  the 
Standards  Committee  of  Parliament,  made 
in  a  report  submitted  December  21,  1841, 
the  British  imperial  standard  of  weight 
was  changed  from  a  Troy  pound  of  5760 
grains  to  an  avoirdupois  pound  of  7000 
grains,  and  a  standard  representing  the 
latter  was  constructed  in  1844  and  duly 
legalized  in  1855.  After  much  discussion 


BRITISH  IMPERIAL  STANDARD     and    a    careful    examination     of    existing 

POUND.    (Exact  size.) 

standards   it  was  found   necessary  to  use 

almost  exclusively  two  platinum  weights,  one  belonging  to  the 
Eoyal  Society  and  the  other  to  Professor  Schumacher,  whose 
values  were  accurately  known  in  terms  of  the  lose  standard. 
The  new  standard,  which  is  indeed  the  present  imperial  standard, 
is  of  platinum,  cylindrical  in  form,  1*35  inches  in  height,  and 
T15  inches  in  diameter.  Its  density  as  compared  with  distilled 
water  is  21*1572,  and  it  displaces  '403  grains  of  air  under 
standard  conditions.1  It  has  a  slight  groove  or  channel  near  its 
upper  surface  by  which  it  may  be  moved  with  a  fork  of  ivory,  and 

XW.  H.  Miller,  "On  the  Construction  of  the  New  Imperial  Standard  Pound, 
etc.,"  Philosophical  Transactions  (London),  1st  June,  1856.  H.  W.  Chisholm, 
Weighing  and  Measuring  (London,  1877). 


STANDARDS   AND   COMPARISON  249 

bears  on  its  upper  surface  the  inscription  "P.S.  1844, 1  lb.,"  the  letters 
signifying  Parliamentary  Standard.  Copy  No.  5  was  presented  to 
the  United  States  in  1856.  The  British  units  of  capacity,  the 
gallon  and  the  bushel,  are  based  on  the  fact  that  an  imperial 
gallon  represents  the  volume  occupied  by  ten  imperial  pounds  of 
distilled  water  at  62  degrees  Fahrenheit  and  a  barometric  pressure 
of  30  inches,  while  the  bushel  is  eight  gallons,1  The  imperial 
standard  gallon  bears  the  date  of  1828  and  is  of  brass,  with  a 
diameter  equal  to  its  depth.  The  imperial  bushel  standard  is  of 
gun-metal,  with  a  diameter  twice  that  of  the  depth,  these  latter 
dimensions  being  selected  on  account  of  the  applicability  to  the 
use  for  the  measure  of  grain.  It  dates  from  1824,  and  was 
verified  in  the  following  year. 

The  French  standard  of  length  previous  to  the  completion  of 
the  Meter  of  the  Archives  was  the  Toise  de  Perou,  to  which 
reference  has  already  been  made.  It  was  constructed  for  use  in 
making  the  base  measurements  for  determining  the  length  of  the 
Peruvian  arc  of  the  meridian  and  the  verification  of  the  arc 
passing  through  Paris,  being  derived  from  the  Toise  du  Grand 
Chatelet,  which  dated  back  to  1668.  This  latter  standard  was  a 
bar  of  iron  which  was  fixed  in  the  wall  of  the  Grand  Ch&telet, 
forming  an  inside  end  standard  by  which  all  scales  could  be  tested 
by  simply  placing  them  between  the  limiting  ends.  This  naturally 
deteriorated  from  exposure  and  wear,  and,  as  a  result,  the  Toise 
de  Perou  was  substituted  for  the  Toise  du  Grand  Chatelet,  as  the 
French  standard  of  length,  in  1766,  and  is  now  preserved  at  the 
Observatory  in  Paris.  It  is  an  end  standard  of  polished  iron, 
somewhat  greater  than  a  toise  in  length  and  of  rectangular 
section,  17  lignes  in  breadth  and  4^  lignes  in  thickness.  At  each 
end  of  the  bar  a  rectangular  portion  extending  to  a  line  midway 
of  the  breadth  was  removed,  and  the  standard  distance  was  taken 
between  the  edges  of  the  remaining  portion  of  the  bar,  at  a  point 
about  one  ligne  from  the  median  line.  On  the  longer  part  of  the 
bar  two  lines  were  traced,  with  points  marked  at  their  centers,  so 
that  the  distance  between  them  was  exactly  a  toise,  with  the  result 
that  an  end  standard  was  combined  in  the  same  metal  bar  with 
the  more  exact  line  standard, — there  being,  however,  a  difference 

1  Henry  Kater,  "Verification  of  Standard  Gallon,"  Philosophical  Transactions 
(London),  1826. 


250    EVOLUTION   OF   WEIGHTS    AND   MEASURES 

between  the  two  scales  of  about  '1  of  a  millimeter,  a  quantity 
which  was  readily  negligible  in  the  metrology  of  those  days. 
The  bar  was  standard  at  a  temperature  of  13°  Keaumur  (16°*25  C. 
or  61°'25  F.)  and  has  been  found  equal  to  1 '949036  meter  at  0°  C. 

The  French  standards  of  weight  were  a  series  of  weights 
known  as  the  Pile  of  Charlemagne,  and  dating  back  to  the  reign 
of  that  king  (about  789).  Together  they  aggregated  50  marcs, 
as  the  unit  of  the  series  was  termed,  or  25  livres  poids  de  marc 
(pounds),  and  in  standardizing  weights  the  sum  of  the  pile  was 
usually  taken  as  the  standard.  These  weights  are  now  preserved 
in  the  Conservatoire  des  Arts  et  Metiers  at  Paris,  and  have 
figured  in  many  comparisons.1 

With  the  experience  which  the  French  scientists  had  gained 
in  their  brilliant  geodetic  work  during  the  18th  century,  it  was 
possible  to  employ  new  and  more  accurate  standards  of  length 
in  the  measurements  of  the  base  lines.  Accordingly,  for  the 
purpose  of  making  this  fundamental  measurement  in  determining 
the  length  of  the  earth's  quadrant,  four  compound  standard  bars 
of  novel  form  were  designed  and  constructed  by  Borda,  each 
of  which  was  two  toises  in  length,  six  lignes  in  width  and  almost 
one  ligne  in  thickness.2  Each  bar  consisted  of  a  strip  of  platinum 
connected  permanently  at  one  end  with  a  strip  of  copper,  which 
otherwise  was  free  to  move  longitudinally  as  it  expanded  or 
contracted.  At  the  opposite  end  the  copper  was  cut  away  for 
a  short  distance  and  a  movable  rod  of  platinum  was  provided,  so 
that  an  exact  and  variable  setting  could  be  made  by  means  of 
a  divided  scale  and  vernier.  As  the  two  metals  had  unequal 
coefficients  of  expansion,  it  was  possible,  by  determining  their 
relative  expansion,  as  indicated  by  a  graduated  scale  and  vernier, 
to  obtain  not  only  a  true  measure  of  length,  but  also  the 
temperature  of  the  bar.  This  was  accomplished  by  first  standard- 
izing the  bars  in  the  laboratory  and  measuring  the  relative 
expansion  corresponding  to  a  certain  number  of  degrees.3  In 

1  See    C.    Mauss,    La   Pile  de    Charlemagne   (Paris,    1897).      A   mathematical 
discussion  of  these  weights. 

2  See  Borda,  "  Experiences  sur  les  regies  destinees  a  la  mesure  des  bases  de  1'arc 
terrestre,"  Delambre  and  Me*chain,  Base  du  Systeme  Metrique,  vol.  iii.  p.  313. 

3  These  bars  of  Borda  were  studied  and  standardized  by  Lavoisier.     See  Chisholm 
in  Nature  (London),  vol.  ix.   p.   185,  Jan.  8,  1874.     See  also  Dumas,    Works  of 
Lavoisier,  vol.  v. 


STANDARDS   AND   COMPARISON  251 

use  in  the  field,  these  bars  were  placed  end  to  end  and  were 
carefully  levelled.  One  of  them  was  considered  as  a  standard, 
and  to  this  all  measurements  were  referred,  including  that  of 
the  seconds'  pendulum,  and  when  the  length  of  the  meter  was 
evaluated,  it  was  obtained  in  terms  of  the  fraction  ('256537) 
of  this  modulus.1 

Compensated  bars  of  this  form  found  increased  use  in  the 
measurement  of  base  lines  in  geodetic  surveys  until  well  into 
the  19th  century,  though  they  have  been  largely  displaced  by  the 
employment  of  bars  of  a  single  material,  or  steel  tapes  or  wires 
whose  temperature  coefficients  are  accurately  known.  In  the  case 
of  the  metallic  bars,  in  one  of  the  most  accurate  base  measurements 
to  which  reference  has  already  been  made,  viz.,  that  at  Holton, 
Mich.,  which  was  made  in  connection  with  the  transcontinental 
survey  of  the  United  States,  the  distance  was  measured  by  means 
of  a  bar  carried  in  a  trough  of  melting  ice.2 

In  passing  from  these  standards  of  Borda  to  the  meter,  use 
was  made  of  the  comparator  of  the  Committee,  and  that  of 
Lenoir,  already  described.  A  provisional  standard  of  brass,  first 
constructed,  served  as  a  means  of  connecting  the  two  measure- 
ments. Finally,  when  sufficient  data  had  been  obtained  and 
computed  to  justify  the  construction  of  a  definite  standard,  it 
was  made  from  a  mass  of  platinum  as  nearly  pure  as  possible 
and  of  a  rectangular  section.  It  was  an  end  standard  4  milli- 
meters in  thickness  and  25  millimeters  in  breadth  becoming  the 
Meter  of  the  Archives.3  From  the  same  material  and  at  the 
same  time  were  constructed  two  other  standards,  which  differed 
only  in  having  a  thickness  of  3'5  millimeters.  These  have  since 
been  known  as  the  Meter  of  the  Conservatory  and  the  Meter 
of  the  Observatory.4 

1  Benoit,  "  Dela  Precision  dans  la  Determination  des  Longueurs  en  Metrologie," 
Rapports  presented  au  Congres  International  de  Physique  (Paris,  1900),  vol.  i. 
p.  34.    Bigourdan,  Le  Systeme  Metrique  (Paris,  1900),  p.  83.    C.  Wolf,  "  Recherches 
historiques  sur  les  etalons  des  poids  et  mesures  de  1'Observatoire,"  Annales  de 
I'Observatoire  (Memoires),  Paris,  vol.  xvii.  p.  C  36  et  seq. 

2  See  note  ante,  p.  141,  chapter  v. 

:5For  Cross-section  see  illustration  on  p.  252.  No.  1  is  the  Meter  of  the 
Archives. 

4C.  Wolf,  "Recherches  historiques  sur  les  etalons  des  poids  et  mesures  de 
I'Observatoire,"  Annales  de  I'Observatoire  (Memoirs),  vol.  xvii.  p.  52. 


252     EVOLUTION   OF   WEIGHTS   AND   MEASURES 

The  construction  of  the  actual  meter  was  accomplished  by 
using  a  number  of  auxiliary  rules,  which  being  placed  end  to 
end  and  compared  both  among  themselves  and  with  the  modulus, 
enabled  the  true  length  of  the  meter  to  be  obtained.  This 
proceeding  involved  considerable  careful  mathematical  work  as 
well  as  manipulative  skill,  and  was  accomplished  with  a  remark- 
able degree  of  precision,  considering  the  apparatus  at  the  disposal 
of  the  investigators.  In  fact,  it  is  fair  to  say  that  modern  work 
of  this  character  is  more  exact  only  through  the  improved  instru- 
ments that  an  advance  in  mechanical  and  scientific  knowledge 
has  made  possible,  rather  than  in  any  greater  skill  and  carefulness 
on  the  part  of  the  observers. 

Although  a  large  number  of  standards  of  a  secondary  character 
were  constructed  by  the  different  bureaus  established  for  this 
purpose  by  the  French  Government  as  well  as  by  instrument 
makers,  but  little  advance  was  made  as  regards  their  form  and 
general  character.  In  most  of  them  the  rectangular  shape  was 
preserved,  and  though,  by  the  use  of  the  microscope,  a  more 
accurate  division  was  possible,  yet  no  standards  of  high  precision 
were  attempted.  When,  however,  the  custody  of  the  standards 
and  their  verification  was  assigned  to  the  Conservatoire  des  Arts 
et  Metiers,  more  interest  was  taken  in  this  work,  and  with  the 
installation  of  new  comparators,  the  scientific  staff  of  that  institu- 
tion began  researches  which  led  to  substantial  improvements. 
It  was  due  to  M.  Tresca,  who  was  Assistant  Director,  that  a 
thorough  study  of  the  shape  and  material  of  standards  was 
undertaken,  the  results  of  which  were  placed  at  the  service  of 
the  International  Commission,  when  it  assembled  in  1870.1 

The  French  Committee,  of  which  he  was  a  member,  recom- 
mended in  preparing  the  specification  for  the  international  meter, 
that  the  new  standard  should  be  a  line  standard,  having  a  cross- 
section  sufficient  in  form  and  dimensions  to  preserve  accurately 
the  shape  of  the  bar,  and  that  its  coefficient  of  expansion  should 
be  as  nearly  as  possible  that  of  the  meter  of  the  Archives.  The 
platinum  which  went  to  make  up  this  original  standard  contained 
also  iridium,  together  with  a  small  amount  of  palladium,  and 
it  was  deemed  desirable,  in  constructing  a  new  prototype,  to 

aSee   Tresca,   Appendix   7,   Annales  du  Conservatoire    des    Arts  et   Metiers, 
vol.  x.  1873. 


STANDARDS   AND   COMPARISON 


253 


employ  an  alloy  of  platinum,  with  one-tenth  part  of  iridium,  as 
devised  by  H.  Sainte-Claire  Deville,  since  as  such  a  combination 
filled  the  required  conditions  of  inalterability,  homogeneity, 


r  i 


12 


CROSS-SECTIONS  OF  STANDARDS  (STUDIED  BY  TRESCA). 

1.— Meter  of  the  Archives.  8.— Provisional  Standard  of  Platinum  Iridium. 

9,  10,  12.— H  Standards.  13,  14,  15.— X  Standards. 

durability,  and  small  expansibility  under  the  influence  of  tem- 
perature. In  addition,  it  was  susceptible  of  taking  a  high  polish, 
and  possessed  numerous  other  physical  and  chemical  advantages 
which  made  it  particularly  suitable  for  this  purpose.1 

1  Bigourdan,  Le  Systeme  M&rique,  p.  274. 


254    EVOLUTION   OF   WEIGHTS   AND   MEASURES 

In  preparing  the  standards  of  length,  it  was  realized  by  the 
Commission  at  the  outset  that  two  essential  conditions  must 
be  fulfilled,  viz.,  that  the  metal  bars  should  be  as  rigid  as  pos- 
sible, without  employing  such  a  quantity  of  the  platinum  alloy 
as  would  make  their  cost  prohibitive,  and,  secondly,  that  the 
lines  marking  the  divisions  must  be  placed  in  the  plane  of  the 
neutral  fibres.  M.  Tresca,  who  had  given  the  subject  of 
standards  careful  study,  reported  to  the  Commission  on  their 
form,  and  stated  the  essentials  which  must  be  observed  in  the 
construction  of  a  new  standard  meter.  He  called  attention  to 
the  fact  that  it  was  necessary  that  the  distance  between  the 
two  limiting  lines  should  lie  entirely  in  a  plane  which  would 
contain  the  various  centres  of  gravity,  and  this  condition  could 
only  be  obtained  by  making  the  bar  of  such  cross-section  that 
it  would  have  the  greatest  rigidity.  He  also  deemed  it  essential 
that  the  cross-section  should  be  uniform  throughout  the  length 
of  the  bar,  and  that  the  median  plane  on  which  the  lines  were 
traced  should  be  available  for  tracing  the  necessary  divisions, 
and  for  observation  with  the  microscope  of  the  comparator.  M. 
Tresca  carried  on  a  series  of  experiments  and  investigations  with 
bars  of  different  cross-sections  for  which  he  calculated  the 
mechanical  constants,  and,  as  a  result  of  the  studies,  he  came 
to  the  conclusion  that  the  most  suitable  form  for  the  standards 
of  length  was  the  bar  of  X  section,  as  shown  in  the  accompany- 
ing figures. 


CROSS-SECTION  OF  STANDARD  METER  BARS.    (Exact  size.) 
1.— Line  Standard.  2.— End  Standard. 

It  will  be  seen  from  the  illustration  that  the  median  plane, 
or  plane  of  the  neutral  fibres,  lies  exactly  in  the  center  of  the 
bar,  and  is  available  for  marking  any  necessary  lines  or 
divisions.  This  is  the  case  with  the  line  standard.  For  the  end 


STANDARDS   AND   COMPARISON  255 

standard  he  adopted  a  somewhat  similar  section,  but  with  the 
cross-bar  relatively  higher,  so  that  the  median  plane  passed 
through  its  center  instead  of  being  situated  in  its  upper  surface, 
as  in  the  case  of  the  line  standard.  The  section  in  either  case 
would  be  included  in  a  square  20  mm.  on  each  side,  and  the 
diagram  represents  accurately  the  actual  size  and  figure  of  the 
section.1 

As  compared  with  the  Meter  of  the  Archives,  the  new  stan- 
dard proposed  by  Tresca  had  a  profile  1'509  times  as  great, 
so  that  the  actual  quantity  of  material  involved  was  but  slightly 
more  than  a  third,  but  the  form  of  construction  made  possible 
far  greater  strength  and  rigidity,  while  at  the  same  time  the 
standard  distance  was  measured  in  the  neutral  plane.  These 
recommendations  were  duly  adopted,  the  material  was  prepared 
according  to  the  above  specifications,  and  the  bars  were  delivered 
to  the  Conservatoire  des  Arts  et  Metiers,  where  the  standards 
were  constructed  by  the  French  section  under  the  terms  of  the 
international  agreement. 

In  the  comparison  of  the  prototype  meters  among  themselves 
and  with  the  international  standard,  the  first  step  was  to  con- 
struct a  provisional  meter,  whose  constants  were  determined 
directly  in  terms  of  the  Meter  of  the  Archives.  For  this  purpose 
a  comparator  with  a  transverse  movement  was  employed,  while 
for  making  the  definitive  marks  on  the  bars  a  longitudinal 
comparator  was  used.  The  comparisons  between  the  Meter  of 
the  Archives  and  the  provisional  meter  were  made  at  the  Conser- 
vatoire des  Arts  et  Metiers.  The  standard  bars  were  taken  to  the 
Bureau  International,  where  was  made  a  series  of  comparisons 
which  established  their  relations  to  each  other,  as  well  as  to  the 
international  prototype.2  Of  the  thirty  bars  thus  examined,  the 
one  that  approached  most  nearly  the  length  of  the  Meter  of 
the  Archives  was  selected  as  the  international  prototype,  and 
a  new  scale  was  chosen  to  take  its  place  in  the  series  of 

^uillaume,  La  Convention  du  Metre  (Paris,  1902),  pp.  15-18;  Benoit,  "  De 
la  Precision  dans  la  Determination  des  Longueurs  en  Me"trologie,"  Rapport^ 
Congres  de  Physique  (Paris,  1900),  tome  i.  p.  48. 

2 See  U.S.  Coast  and  Geodetic  Survey  Report,  1890,  Appendix  18,  pp.  743  et  setj., 
for  a  description  of  the  construction  of  the  standard  meter  bars  ;  also  Bigourdan, 
Le  Systeme  Metrique. 


256    EVOLUTION   OF   WEIGHTS   AND   MEASURES 

comparisons.  As  a  result  of  these  comparisons,  the  probable  error 
of  a  single  comparison  was  stated  at  ±0*12  /x — the  probable  error 
in  the  length  of  any  one  of  the  standards  being  stated  at 
±0'04  p.1  From  the  result  of  many  years  of  comparison  at  the 
Bureau  International,  the  conclusion  is  reached  that  the  length 
of  a  standard  can  be  absolutely  guaranteed  to  an  exactitude  of 
about  '2  micron  at  all  usual  temperatures.2 

In  the  construction  of  standards  of  weights,  the  instrument 
makers  of  the  eighteenth  century  had  gradually  become  more 
proficient,  and  their  work  partook  of  greater  precision,  both  in 
the  weights  themselves  and  in  the  balances.  Nevertheless,  no 
particular  features  are  worthy  of  note  until  the  kilogram  of  the 
Archives  was  constructed.  This  unit  of  weight,  as  we  have  seen, 
was  defined  as  the  "  weight  of  a  cubic  decimeter  of  distilled  water, 
taken  at  its  maximum  density  and  weighed  in  a  vacuum."  To 
realize  such  a  definition  in  a  standard  would  apparently  involve 
the  construction  of  a  cubic  vessel  whose  side  was  exactly  a 
decimeter,  and  then  ascertaining  the  weight  of  water  contained 
therein.  A  measurement  of  this  kind  could  be  made  by  taking 
a  vessel  of  regular  form  and  known  interior  dimensions,  but  to 
determine  its  volume  accurately  by  any  process  of  measuring 
was  a  difficult,  if  not  an  impossible  proceeding.  Kecourse  was 
had,  accordingly,  to  the  law  of  Archimedes,  which  states  that  a 
body  immersed  in  a  fluid  loses  an  amount  of  weight  equal  to 
the  weight  of  the  volume  of  the  fluid  which  it  displaces.  Con- 
sequently, in  order  to  determine  the  weight  of  the  displaced 
water,  it  was  necessary  to  weigh  a  solid  body  of  regular  form, 
first  in  air,  reducing  to  vacuum,  and  then  in  water,  making 
suitable  provision  or  correction  for  its  temperature.  In  order 
to  determine  exactly  the  volume  of  such  a  body,  it  must  be 
constructed  in  a  regular  geometric  form,  such  as  a  cube  or  a 
cylinder.  The  latter  form  was  adopted  in  making  the  standard 
of  weight  by  the  Committee  of  the  Meter,  and  Lefevre-Gineau, 
with  the  assistance  of  Fabbroni,  standardized  a  hollow  cylinder 
of  brass,  which  was  constructed  for  them  by  Lenoir.  It  was 
243*5  millimeters  in  height  and  diameter,  and  thus  had  a  volume 

1  Benoit,    Jtapports,    Congres   International  de  Physique  (Paris,   1900),   vol.  i. 
p.  63. 

-Ibid.  p.  66. 


STANDARDS   AND    COMPARISON  257 

slightly  in  excess  of  eleven  cubic  decimeters,  and  had  a  weight  in 
water  of  about  200  grams.1     The  dimensions  of  the  cylinder  were 
obtained  with  a  lever  comparator  from  a  scale  equal  to  the  -^ 
part  of  the  modulus  (the  double  toise  standard  of  Borda).     As  a 
result  of  these  experiments,  a  theoretical  value  of  18827*15  grains 
{poids  de  marc)  was  assigned  to  the  kilogram,  and  such  a  weight 
was  constructed  in  pure  platinum  to  be  the  prototype  standard.2 
Unfortunately,   no   record  has  been  left   to  us  of  the    methods 
•employed  in  constructing  such  a  standard.      It  is  known,  how- 
ever, that  at  the  time  when  the  platinum  was  prepared  for  the 
four  standard  meter  bars,    material   was   made    ready    for  four 
•cylinders  destined  for  the  standard  kilogram.     After  adjustment, 
one  of  these  was  taken,  and  has  since  survived  as  the  Kilogram 
of  the  Archives.      It  is  unquestionable,  however,  that  the  same 
balance  and  weights  employed  in  determining  the  weight  of  a 
cubic  decimeter  of  water  were  used  in  these  latter  operations.3 
During   the  first  half  of  the    19th  century,  with  the  growth 
of    experimental   physics    and   with  improvements  of  apparatus, 
new  methods  giving  a  high  degree  of  precision  were  available  for 
use    with    the   balance.       Consequently,  in  the   construction   of 
weights  and  in  their  reference  to  standards,  much  more  precision 
was  obtained  than  ever  previously.     This,  however,  did  not  cause 
any  marked  demand  for  new  metric  standards,  although  various 
physicists  were  of  the  opinion  that  the  kilogram  did  not  repre- 
sent accurately  the  mass  of  a  cubic  decimeter  of  water.     These 
determinations,  however,  varying  as  they  did — being  both  greater 
and  smaller  than  the  Kilogram  of  the  Archives— did  not  inspire 
any  greater   degree    of  confidence.     Accordingly,    when   it    was 
proposed    to   construct   new   standards    for   the   meter  and    the 
kilogram,  it  was  decided  to  use  the  Kilogram  of  the  Archives 
as    the  basis,  and    then    by   subsequent   experiments  determine 
its  relation  to  the  mass  of  a  cubic  decimeter  of  water  at  its  tem- 
perature of  maximum  density.      Accordingly,  the  International 
Commission     made     arrangements    for     such     an    investigation. 

1Guillaume,   La  Convention  du  Metre,  p.  5. 

2  For  full  description  of  the  determination  of  the  standard  of  mass,  see 
Delambre  and  Me^hain,  Base  du  Systeme  MetriquA,  vol.  iii.  pp.  579-638; 
Bigourdan,  Le  Systeme  Metrique,  p.  107. 

3Bigourdan,  Le  Systeme  M&rique,  p.  159. 


258     EVOLUTION  OF   WEIGHTS  AND  MEASURES 

To  this  body,  in  1879,  three  cylinders  of  platinum-iridium 
alloy,  designed  for  standard  kilograms,  were  delivered,  and 
were  then  compressed  in  a  powerful  coining-press  of  the 
Paris  Mint.  They  were  then  given  to  an  instrument  maker 
for  approximate  adjustment,  and  samples  of  the  material  were 
submitted  to  chemical  analysis  by  Stas  and  Sainte-Claire 
Deville,  it  having  been  found  by  experiments  at  the  Ecole 
Normale  that  the  final  density  was  21 '55.  The  first  adjustment 
was  made  with  the  kilograms  of  the  Paris  Observatory,  which 
were  copied  from  that  of  the  Archives,  and  for  this  purpose 
a  balance  of  the  Ecole  Normale  Superieure  was  employed.  After 
the  three  standards  had  received  their  final  adjustment  at  the 
hands  of  M.  A.  Collet,  they  were  then  compared  with  the  Kilo- 
gram of  the  Archives,  with  the  standards  of  the  Observatory  and 
the  Conservatoire,  and  with  the  standard  kilogram  of  Belgium,, 
and  then  final  comparisons  were  made  at  the  Paris  Observatory,, 
both  the  French  section  and  the  International  Committee  being 
duly  represented.1 

The  volume  of  these  three  new  standards  was  determined 
by  hydrostatic  weighings,  and  compared  with  that  of  the  standard 
of  the  Archives,  which,  however,  was  determined  by  other  methods, 
as  it  was  not  deemed  advisable  to  place  it  in  water.2  The  work 
was  finished  October  18,  1880,  when  the  Committee  submitted  a 
report  covering  other  duties. 

After  a  careful  examination  of  these  three  kilograms  among 
themselves,  and  with  the  standard  kilogram  of  the  Archives,  the 
committee  deemed  it  wise  to  select  one  which  was  known  as- 
Kill  as  the  standard  kilogram,  rather  than  to  make  a  series  of 
additional  comparisons  with  the  other  kilograms,  to  be  constructed 
as  national  standards,  in  the  course  of  which  the  platinum-iridium 
cylinder  would  doubtless  experience  a  certain  amount  of  injury. 
Accordingly,  this  was  adopted  in  a  formal  resolution,  at  a  meet- 
ing held  October  3,  1883,  and  that  kilogram  has  since  been 
designated  by  jl,  although  it  bears  no  mark.3 

In  the  following  year,  after  several  attempts  had  been  made  to 
secure  an  alloy  of  the  necessary  purity,  satisfactory  material 

iGuillaume,  La  Convention  du  Metre  (Paris,  1902),  p.  123. 

zlbid.  p.  124. 

3 Bigourdan,  Le  Systeme  Metrique  des  Poids  et  Mesures  (Paris,  1901),  p.  365. 


STANDARDS   AND    COMPARISON  259 

suitable  for  the  national  prototypes  was  delivered  in  the  form  of 
forty  cylinders.  These  were  worked  down  to  approximately  the 
exact  weight,  and  finished  under  the  direction  of  the  members  of 
the  commission  and  an  elaborate  series  of  comparisons  was  under- 
taken.1 

The  weighings  were  effected  by  means  of  the  Rueprecht  and 
Bunge  balances  already  described,  the  latter  being  employed 
when  comparisons  were  made  with  the  international  prototype, 
which,  of  course,  was  preserved  most  carefully  from  any  deterio- 
rating influences.  The  constants  were  calculated  separately  for 
each  standard,  and  they  were  found  to  agree  within  a  limit  of 
one  milligram,  and  were  accepted  by  the  International  Committee, 
this  decision  being  formally  sanctioned  at  the  International  Con- 
ference in  1889.  Originally  it  had  been  determined  to  insist  on 
an  accuracy  of  '2  of  a  milligram  for  each  kilogram,  but  in  certain 
cases  it  was  found  that  the  polishing  had  been  carried  on  too 
vigorously,  and  it  was  accordingly  found  necessary  to  fix  the  limit 
€>f  accuracy  at  one  milligram,  within  which  limits  the  forty 
standards  all  fell.  For  example,  those  given  to  the  United 
States,  in  the  drawing  by  lot  (Nos.  4  and  20)  were  found  to  have 
an  error  of  —  '075  milligram  and  —  '039  milligram  respectively.2 

The  permanence  of  the  national  standards  of  mass  is  no  less 
important  than  that  of  the  standards  of  length.  After  about 
ten  years  there  was  made  at  the  Bureau  International  a  com- 
parison of  eight  standards  from  seven  different  nations  with  the 
working  standards  of  the  Bureau,  and  it  was  found  that  the 
deterioration  experienced  was  barely  appreciable,  ranging  as  it 
did  from  '027  milligram  in  the  case  of  one  of  the  Belgian 
standards,  to  '001  of  a  milligram  in  the  case  of  that  from 
Roumania.  It  was  possible  that  the  deterioration  in  the  case 
of  some  of  the  kilograms  which  had  experienced  considerable 
usage,  was  as  much  as  *04  of  a  milligram,  but  it  was  believed  that 
the  future  would  not  show  as  great  an  amount  of  change.3 

The  idea  of  the  founders  of  the  Metric  System  to  establish  a 
unit  of  length  which  would  be  absolutely  invariable,  by  means  of 
its  reference  to  the  dimensions  of  the  earth,  and  also  by  reference 

^uillaume,  La  Convention  du  Metre,  p.  125.  zlbid.  p.  126. 

3  Ibid.  p.  127.  Also  Report  by  M.  Benoit  in  Proces-  Verbaux  des  Stances  de 
1900,  Comites  International  des  Poids  et  Mesures.  See  also  Proces-  Verbaux,  1905. 


260     EVOLUTION  OF  WEIGHTS  AND  MEASURES 

to  the  seconds'  pendulum,  was  not  destined  to  survive.  It  soon 
was  seen,  in  view  of  subsequent  researches,  that  the  trigono- 
metrical operations  on  which  the  length  of  the  meter  was  based 
were  not  carried  on  with  an  exactitude  required  by  modern 
methods  of  geodetic  work,  and  that,  as  a  result,  the  standard  was 
in  error  by  about  '1  millimeter.  This  did  not  detract  from  the 
usefulness  of  the  system,  but  it  did  require  the  abandonment  of 
the  idea  of  referring  the  meter  to  the  ten-millionth  of  the  earth's 
quadrant  as  a  natural  standard.  A  century  after  the  Metric 
System  was  established,  it  was  found  possible  to  realize  the 
condition  of  reference  to  a  natural  and  invariable  standard,  which 
was  at  that  time  thought  so  fundamental,  and  the  meter  was 
defined  in  terms  of  wave-length  of  light,  after  a  series  of  most 
elaborate  experiments  carried  on  at  the  International  Bureau  of 
Weights  and  Measures  by  Professor  A.  A.  Michelson,  later  of  the 
University  of  Chicago,  who  had  previously  distinguished  himself 
by  his  accurate  determination  of  the  velocity  of  light. 

The  fundamental  idea  of  using  a  wave-length  of  light  was  by 
no  means  new,  as  a  unit  of  this  nature  had  been  proposed  by 
J.  Clerk  Maxwell,1  who  suggested  that  a  system  of  absolute 
units  could  be  founded  on  the  following  basis : 

As  a  unit  of  length,  the  wave-length  of  some  determined  kind 
of  light  in  vacuo, 

As  a  unit  of  time,  the  period  of  vibration  of  this  light, 

As  a  unit  of  mass,  the  mass  of  a  single  molecule  of  a  specified 
substance. 

By  determining  a  unit  of  length  in  terms  of  wave-lengths  of 
light,  a  standard  would  be  obtained  independent  of  any  gradual 
contraction  of  the  terrestrial  globe,  which  naturally  would  produce 
a  change  in  the  length  of  the  meridian,  or  other  terrestrial 
disturbance.  Likewise,  it  would  be  independent  of  molecular 
changes  occurring  in  a  metallic  bar,  and  naturally  affecting  its 
dimensions.  The  length  of  a  wave  of  light  would  under  all 
conditions  be  most  invariable,  as  it  depends  solely  on  the 
elasticity  of  the  ether.  Such  a  unit,  then,  gives  us  a  means  of 
establishing  the  permanent  values  of  the  meter,  as  by  determining 
its  length  in  these  minute  distances  represented  by  the  vibration 
of  particles  producing  one  kind  of  light,  we  have  a  much  better 

1  Maxwell,  Electricity  and  Magnetism  (third  edition,  Oxford,  1891),  vol.  i.  pp.  3,  4. 


STANDARDS    AND    COMPARISON  261 

means  of  fixing  its  invariability  than  by  comparing  it  with  the 
length  of  a  meridian  or  with  the  seconds'  pendulum. 

In  order  to  define  the  standard  of  length  in  terms  of  the 
wave-length  of  light,  a  study  of  different  sources  of  light  was 
essential,  and  was  carried  on  by  Professor  Michelson  with  great 
thoroughness.  For  this  purpose,  he  used  the  luminous  vapors  of 
metals  produced  by  the  passage  of  an  electric  current  from  the 
induction  coil  through  a  vacuum  tube.  By  a  process  of  elimina- 
tion, he  found  that  the  most  suitable  source  of  light  was  the 
spectrum  furnished  by  the  metal  cadmium,  which  gave  a  series  of 
lines  valuable  for  his  purpose.  The  visible  spectrum  of  this 
metal  consisted  of  four  groups  of  lines, — one  red,  which  was  single 
and  also  fine ;  the  second,  a  series  of  fine  green  lines ;  the  third, 
a  blue  line ;  the  fourth,  a  violet  line.  In  his  early  experiments, 
Professor  Michelson  used  the  green  rays,  but  in  later  work, 
especially  by  M.  Hamy  and  M.  Chappuis,  the  others  were 
employed  and  greater  precision  was  attained.1 

Professor  Michelson's  method  is  based  on  the  fact  that  inter- 
ference is  produced  in  a  beam  of  light  after  two  of  its  component 
parts  are  compelled  by  means  of  reflection  to  travel  distances 
slightly  unequal.  The  earliest  application  of  this  principle  of 
interference  in  metrology  was  when  Fizeau  endeavored  to 
determine  accurately  the  coefficients  of  expansion  of  samples  of 
various  substances.  By  placing  a  plano-convex  lens  over  and 
very  close  to  the  terminal  surface  of  the  body  to  be  studied,  and 
causing  a  beam  of  sodium  (yellow)  light  to  fall  from  above  on  the 
lens,  he  was  able  to  obtain  the  optical  phenomenon  known  as 
interference  by  observing  the  reflected  beam.  This  was  similar 
in  nature  to  the  well-known  experiment  called  Newton's  rings, 
where  the  difference  in  path  of  the  rays  of  light  reflected  from 
the  surface  of  a  body  and  those  reflected  from  the  surface  of  the 
lens  produces  interference.  The  reason  for  this  is  found  in  the 
fact  that  waves  of  monochromatic  light,  when  so  impeded  that  a 
part  of  them  lose  a  half-wave  length  or  some  odd  number  of 
half-wave  lengths,  will  neutralize  each  other,  and  consequently 
produce  darkness  when  they  reach  a  certain  point.  This  is  due 
to  the  particles  at  this  point  being  under  the  influence  of  waves 
in  opposite  phases.  If,  on  the  other  hand,  where  they  meet,  the 

1  Guillaume,  La  Convention  du  Metre.,  p.  147. 


•262     EVOLUTION  OF  WEIGHTS  AND  MEASURES 

number  of  half-wave  lengths  is  even,  there  is  increased  effect, 
which  is  manifested  by  greater  brightness.  In  the  case  of  a  lens, 
arranged  as  above,  there  would  be  a  series  of  alternate  light  and 
dark  concentric  rings.  If  white  light  is  used,  these  rings  will 
show  spectral  colors,  which  become  complex  with  an  increase  in 
distance  from  the  center.  With  such  an  arrangement,  Fizeau  was 
able  only  to  measure  short  distances,  which  did  not  exceed  12  or 
15  mm.  in  length.  His  method  was  useful,  however,  in  measuring 
accurately  the  screw  of  the  micrometer  of  the  comparators.1 

Using  the  same  idea,  but  developing  it  practically,  Professor 
Michelson  was  able  to  measure  the  length  of  the  meter  in  terms 
of  waves  of  light.  Part  of  the  difficulty  was  solved  by  the 
American  physicist  when  he  found  a  suitable  source  of  light,  as 
has  been  described  above,  but  it  was  largely  due  to  his  ingenious 
methods  and  apparatus,  as  well  as  to  his  manipulative  skill,  that 
he  was  able  to  carry  his  plan  to  so  successful  a  conclusion.2  His 
arrangement  was,  in  substance,  as  follows :  Light  from  the  given 
source,  S,  was  allowed  to  fall  on  a  glass  plate  at  A,  ground  so 
that  the  surfaces  were  perfectly  plane  and  parallel.  This  plate 
was  placed  obliquely  to  the  axis  of  the  beam  and  on  the  side  A 
was  silvered,  so  that  it  formed  a  semi-transparent  reflector.  The 
beam  falling  on  this  silvered  surface  was  divided  into  two  parts, 
one  of  which  passed  through  the  silver  film  and  glass,  and  after 
reflection  at  E  in  the  mirror  R  to  a  mirror,  Ny  from  which  it 
was  reflected  back  through  the  glass  plate  to  the  interior 
surface  of  the  film,  where  it  underwent  reflection  again, 
back  through  the  glass  and  to  a  telescope,  T,  so  arranged  as  to 
enable  the  fringes  produced  in  its  field  to  be  observed.  The  other 
part  of  the  beam  was  reflected  at  the  silvered  surface  and  trans- 
mitted through  a  second  glass  plate,  Q,  whose  thickness  was  equal 
to  the  first,  to  a  mirror,  M,  where  it  was  reflected  back  through 
the  first  plate  in  the  same  direction  as  the  first  beam.  Both 

JJ.  Rene"  Benoit,  "Etudes  sur  1'appareil  de  M.  Fizeau  pour  la  mesure  des 
dilatations  appartenant  au  Bureau  International  des  Poids  et  Mesures,"  vol.  ii. 
Travaux  et  Me"moires,  Bureau  International  des  Poids  et  Mesures,  Paris. 

2  Guillaume,  La  Convention  du  Metre  (Paris,  1902),  pp.  146-169.  A.  A.  Michelson, 
"  Determination  expe'rimentale  de  la  valeur  du  metre  en  longueurs  d'ondes 
lumineuses,"  vol.  xi.  Travaux  et  Mdmoires,  Bureau  International  des  Poids  et 
Mesures,  Paris. 


STANDARDS    AND   COMPARISON 


263 


264     EVOLUTION  OF  WEIGHTS  AND  MEASURES 

beams  meeting  at  the  telescope,  interference  phenomena  would 
appear  if  there  were  any  difference  in  the  length  of  their  respective 
paths,  ADFEFDAC  and  ABAC.  By  displacing  one  of  the  mirrors 
by  a  small  amount  through  the  agency  of  a  screw,  this  difference 
of  position  could  be  measured  in  terms  of  wave-length.  The  first 
task  of  the  investigator  was  to  determine  the  length  of  a  very  short 
standard  by  displacing  the  fringes  for  a  counted  number  of  wave- 
lengths. Then  with  this  as  a  standard,  he  would  be  able  to  construct 
a  standard  twice  as  long  and  derive  its  length  in  wave-lengths.  In 
this  way  Professor  Michelson  prepared  a  number  of  standards  of 
lengths,  each  double  the  length  of  another,  so  that  he  was  able  to 
step  from  one  to  the  other  and  at  the  same  time  preserve  the 
original  accuracy,  Finally  he  standardized  a  piece  one  decimeter 
in  length,  and  with  this  he  made  a  comparison  with  the  inter- 
national meter,  displacing  it  ten  times  and  measuring  the  displace- 
ment by  interference  methods  so  as  to  start  from  the  first  line  of 
the  meter  and  then  reach  the  second,  and  so  on  ;  using  three 
different  kinds  of  light,  viz.  the  red,  green,  and  blue  of  the 
cadmium  spectrum,  he  determined  the  wave-length  of  each  or 
the  number  of  times  this  wave-length  was  contained  in  the 
standard  meter.  The  wave-lengths  for  each  color  were  as- 
follows : 

Bed  radiations     1  meter  =  1553163'6  X^   of  which   \R  =  '64384722  /x. 

Green  radiations 1  meter  =  19662497  Ar,   of  which   Ar=  '50858240  /x. 

Blue  radiations    1  meter  =  2083372'1  Afi,   of  which   Afi= '47999107 /z. 

The  accuracy  of  this  work  is  almost  incredible,  as  the 
variation  in  the  measurements  was  only  about  one  part  in  ten 
million.  In  fact,  where  a  precision  of  from  one-fourth  to 
one-fifth  of  a  micron  is  possible  in  the  case  of  determining 
the  relative  length  of  two  standards,  here  is  an  absolute 
measurement  which  gives  the  length  of  a  standard  in  terms 
of  a  natural  unit,  under  conditions  reproducible  at  any  time.  This, 
of  course,  gives  a  permanent  check  on  the  integrity  of  the  meter, 
as  in  the  event  of  the  international  prototype  being  damaged 
or  destroyed,  sufficient  data  is  at  hand  to  enable  such  physicists 
as  may  be  found  at  any  international  laboratory  or  bureau  of 
standards  to  redetermine  this  fundamental  unit.  The  apparatus  of 
Professor  Michelson  represented  the  highest  skill  of  the  instrument 


STANDARDS    AND   COMPARISON  265 

maker,  as  mirrors  and  optical  planes  were  finished  to  a  high 
degree  of  exactitude,  reaching  in  some  cases  an  accuracy  as 
great  as  4OoOO  of  a  millimeter,  or  the  -^  of  the  mean  wave- 
length of  light. 

Just  what  this  work  of  determining  standards  of  length  in 
terms  of  the  wave-length  of  light  means  to  science  can  be  readily 
understood  if  a  moment's  consideration  be  given  to  the  enormous 
mass  of  scientific  and  technical  literature  and  knowledge,  to  the 
numberless  instruments  of  measurement  and  tools  and  appliances 
of  trade.  At  first  thought  it  would  seem  that  if  some  cataclysm 
should  suddenly  destroy  all  these  evidences  of  advancement,  then 
the  poor  individual  who  might  have  survived  would  be  compelled 
to  begin  all  over  again,  and  his  standards  and  units  would 
have  to  be  new,  and  he  would  have  no  means  of  connect- 
ing his  system  with  the  past.  All  the  observations  on 
matters  astronomical  or  terrestrial,  all  that  mass  of  information 
which  it  has  taken  centuries  and  centuries  to  accumulate,  would 
be  hopelessly  lost  because  of  the  break  in  the  standards  of 
measurement.  The  meter  would  be  gone,  the  quadrant  of  the 
earth  no  longer  the  same,  and  apparently  our  last  tie  broken. 
Not  all  the  ties,  for  one,  a  little  one,  remains,  like  hope  in  the 
bottom  of  Pandora's  box.  A  wave  of  light  so  small  that  a 
thousand  would  scarcely  reach  across  the  eye  of  a  needle,  this 
is  the  key  to  the  restoration  of  our  system  of  most  complicated 
and  complete  units.  So  long  as  the  earth  has  a  material  exist- 
ence, so  long  as  there  is  light  and  heat,  so  long  is  man  in 
the  position  to  rebuild  his  system  of  units  and  standards. 

The  work  of  Michelson  in  comparing  the  international  meter 
with  the  wave-lengths  of  light  has  put  our  system  upon  a 
foundation  that  is  as  permanent  as  the  universe.  If  man  were 
transported  to  the  uttermost  confines  of  the  universe,  he  would 
still  have  the  little  waves  of  light,  and  they  would  be  just  the 
same  as  here. 

If  some  day  we  are  able  to  communicate  with  the  dwellers 
upon  some  other  planet,  it  will  be  a  simple  thing  to  communicate 
to  them  our  standard  of  length  and  time  and  mass,  and  with  the 
little  waves  of  light  to  convey  our  message  we  may  ultimately 
impart  our  exact  knowledge  to  them,  and  receive  theirs  in 
return.  The  laws  of  light  motion,  of  gravitation,  of  electricity 


266     EVOLUTION  OF  WEIGHTS  AND  MEASURES 

are  undoubtedly  identical  for  the  whole  universe,  and  given 
the  first  communication  of  another  world  we  would  be 
able  to  establish  a  truly  universal  system  of  units  and  stan- 
dards. By  this  means  inter-planetary  communication  would 
be  placed  upon  a  quantitative  basis,  and  the  omnipresent,  ever- 
lasting, but  ultra-microscopic  wave  of  light  would  be  the 
universal,  unchanging  standard. 


APPENDIX. 

TABLES  OF   CONVERSION  FROM   COMMON  TO  METRIC 

MEASURES,   USEFUL  CONSTANTS  AND 

EQUIVALENTS. 


NOTE. 

UNLESS  otherwise  specified,  the  following  tables  are  based 
on  the  U.S.  Legal  Equivalents.  They  are  derived  for  the 
most  part  from  the  Tables  of  Equivalents  published  by  the 
National  Bureau  of  Standards  of  the  U.S.  Department 
of  Commerce  and  Labor. 


LEGAL  EQUIVALENTS  OF  THE  UNITED  STATES. 

ACT  OF  JULY  28,  1866.     REVISED  STATUTES  3570. 

MEASURES  OF  LENGTH. 


METRIC  DENOMINATIONS  AND  VALUES. 

EQUIVALENTS  IN  DENOMINATIONS  IN  USE. 

Myriameter, 

-     10,000  meters. 

6-2137  miles. 

Kilometer, 

1,000  meters. 

0-62137  miles  or  3,280  feet  and  10  inches. 

Hectometer, 

100  meters. 

328  feet  and  1  inch. 

Dekameter, 

10  meters. 

393-7  inches. 

Meter, 

Decimeter, 
Centimeter, 
Millimeter, 

1  meter, 
-pj  of  a  meter. 
T1517  °f  a  meter. 
TtfVtf  of  a  meter. 

39-37  inches. 
3-937  inches. 
0-3937  inch. 
0-0394  inch. 

MEASURES  OF  CAPACITY. 


METRIC  DENOMINATIONS  AND  VALUES. 

EQUIVALENTS  IN  DENOMINATIONS  IN  USE. 

Names. 

Number 
of  Liters. 

Cubic  Measure. 

Dry  Measure. 

Liquor  or 
Wine  Measure. 

Kiloliter  \ 
orStere/ 

1000 

1  cubic  meter 

1  -308  cub.  yards 

264-17  gallons. 

Hectoliter 

100 

-j^  of  cubic  meter 

/  2  bushels  and  \ 
\     3-35  pecks     / 

26-417  gallons. 

Dekaliter 

10 

10  cubic  decimeters 

9-08  quarts 

2-6417  gallons. 

Liter 

1 

1  cubic  decimeter 

0-908  quart 

1  '0567  quarts. 

Deciliter 

TO- 

3^y  cubic  decimeter 

6-1022cub.  inches 

0-845  gill. 

Centiliter 

1 

TTJU 

10  cubic  centimeters 

0-6102  cub.  inch 

0-338  fluid  ounce. 

Milliliter 

1 

1TTOT7 

1  cubic  centimeter 

0-061  cub.  inch 

0-27  fluid  dram. 

MEASURES  OF  SURFACE. 


METRIC 

DENOMINATIONS  AND  VALUES. 

EQUIVALENTS  IN  DENOMINATIONS  IN  USE. 

Hectare, 
Are, 
Centare, 

-     10,000  square  meters. 
100  square  meters. 
1  square  meter. 

2-471  acres.                             ^ 
119-6  square  yards. 
1,550  square  inches. 

270     EVOLUTION  OF  WEIGHTS  AND  MEASURES 


WEIGHTS. 


METRIC  DENOMINATIONS  AND  VALUES. 

EQUIVALENTS  IN  DE- 
NOMINATIONS IN  USE. 

Names. 

Number  of 

Weight  of  what 
Quantity  of  Water  at 

Avoirdupois  Weight. 

Maximum  Density. 

Millier  or  Tonneau 

1,000,000 

1  cubic  meter 

2204-6  pounds. 

Quintal 

100,000 

1  hectoliter 

220-46  pounds. 

Myriagram 

10,000 

10  liters 

22-046  pounds. 

Kilogram  or  Kilo 

1,000 

1  liter 

2-2046  pounds. 

Hectogram 

100 

1  deciliter 

3-5274  ounces. 

Dekagram 

10 

10  cubic  centimeters 

•3527  ounce. 

Gram 

1 

1  cubic  centimeter 

15-432  grains. 

Decigram 

1 
TT7 

jV  cubic  centimeter 

1-5432  grains. 

Centigram 

1 
T(70" 

10  cubic  milliliters 

0-1543  grain. 

Milligram 

1 

ioi5"o 

1  cubic  milliliter 

0-0154  grain. 

BEITISH  LEGAL   (BOARD   OF  TEADE)  EQUIVALENTS. 

MAY,  1898. 


LINEAR  MEASURE. 


METRIC. 

1  Millimeter  (mm.)  (TITOU"  m-)  = 
1  Centimeter  (TOTJ  m.) 
1  Decimeter  (-j^j-  m.)                   = 

0-03937  Ins. 
0-3937  Ins. 
3-937  Ins. 

1  Meter  (m.) 

(  39-370113  Ins. 
\     3  -280843  Ft. 
I     1-0936143  Yds. 

1  Dekameter  (10m.) 

10-936  Yds. 

1  Hectometer  (100m.) 

109-36  Yds. 

1  Kilometer                                  = 

•62137  Mile. 

IMPERIAL. 


1  Inch 

1  Foot  (12  ins.) 

1  Yard  (3  ft.) 

1  Fathom  (6ft.) 

1  Pole  (54  yds. ) 

1  Chain  (22  yds. ) 

1  Furlong 

1  Mile  (8  furlongs) 


:  25 -400  Millimeters. 
:     0-30480  Meter. 
:     0-914399  Meter. 
=     1-8288  Meters. 
:     5-0272  Meters. 
:  20-1168  Meters. 
:  201 -168  Meters. 
=     1  -6093  Kilometers. 


BRITISH   LEGAL   EQUIVALENTS  271 

SQUARE  MEASURE. 

METRIC. 

1  Square  Centimeter  =       0-15500  Sq.  In. 

1  Sq.  Decimeter  (100  sq.  centimeters)       =      15 '500  Sq.  In. 

1  Sq.  Meter  (100  sq.  decimeters)  =  /  10'7639  S(l-  Ft- 

1     1 -I960  Sq.  Yds. 

1  Are  (100  sq.  meters)  =    119 "60  Sq.  Yds. 

1  Hectare  (100  ares  or  10,000  sq.  meters)  =       2 '4711  Acres. 

IMPERIAL. 

1  Square  Inch  =     6 '4516  Sq.  Centimeters. 

1  Sq.  Ft.  (144  sq.  ins.)  =     9'2903  Sq.  Decimeters. 
1  Sq.  Yard  (9  sq.  ft.)    =       "836126  Sq.  Meter. 
1  Perch  (30i  sq.  yds.)  =  25 "293  Sq.  Meters. 
1  Rood  (40  perches)      =  10'117  Ares. 
1  Acre  (4840  sq.  yds.)  =     0 '40468  Hectare. 
1  Sq.  Mile  (640  acres)  =259  Hectares. 

CUBIC  MEASURE. 

METRIC. 

1  Cubic  Centimeter  =        '0610  Cubic  In. 

1  Cubic  Decimeter  (c.d.)  (1000  cubic  centimeters)  =    61 '624  Cubic  Ins. 

1  Cubic  Meter  (1000  cubic  decimeters) 


IMPERIAL. 

1  Cubic  Inch  =16 '387  Cubic  Centimeter. 

1  Cubic  Foot  (1728  cub.  ins.)=  0'028317  Cubic  Meter. 
1  Cubic  Yard  (27  cub.  ft.)      =  0'764553  Cubic  Meter. 

CAPACITY. 

METRIC. 
1  Centiliter  (T^  liter)  =   '670  Gill. 


1  Deciliter  (^  liter)      =   '176  Pint. 
1  Litre  =  1  '75980  Pints. 

1  Dekaliter  ( 1 0  liters)     =  2  '200  Gallons. 
1  Hectoliter  (100  liters)  =  2 '75  Bushels. 

IMPERIAL. 

1  Gill  =1-42  Deciliter. 

1  Pint  (4  gills)  =    '568  Liters. 

1  Quart  (2  pints)        =  1  '136  Liters. 
1  Gallon  (4  quarts)     =4 '5459631  Liters. 
1  Peck  (2  gallons)       =9 '092  Liters. 
1  Bushel  (8  gallons)    =3 '637  Dekaliters. 
1  Quarter  (8  bushels)  =  2 '909  Hectoliters. 


272     EVOLUTION  OF  WEIGHTS  AND  MEASURES 


WEIGHT. 

METRIC. 

Avoirdupois. 

1  Milligram  Cunnr  grm.)  = 

0-015  Grain. 

1  Centigram  (T  J^  grm.  )  = 

0-154  Grain. 

1  Decigram  (yV  grm.  )       = 

1  -543  Grains. 

1  Gramme  (1  grm.) 

15-432  Grains. 

1  Dekagram  (10  grm.)        = 

5  -664  Drams. 

1  Hectogram  (100  grm.)     = 

3-527  Oz. 

c 

2-2046223  Lb.  oz. 

1  Kilogram  (1000  grm.  )     =  j 

15432-3564  Grains. 

1  Myriagram  (10  kilog.)    = 

22-046  Lb. 

1  Quintal  (100  kilog.) 

1-968  Cwt. 

1  Tonne  (1000  kilog.) 

0-984  Ton. 

Troy. 

i 

0-03215  Oz.  Troy. 

1  Gramme  (1  grm.) 

15-432  Grains. 

Apothecaries'  Weight. 

1  Gramme  (1  grm.) 

0-2572  Drachm. 
0-7716  Scruple. 

I 

15  -432  Grains. 

IMPERIAL. 

Avoirdupois. 

1  Grain  = 

1  Dram 

1  Oz.  (16  drams) 

1  Pound  (16  oz.  or  7000  grains)     = 
1  Stone  (141b.) 
1  Quarter  (28  Ib.) 

1  Hundredweight  (cwt.)  (112  lb.)  = 

1  Ton  (20  cwt.) 

Troy. 
1  Grain 

1  Pennyweight  (24  grains) 
1  Troy  ounce  (120  penny  weights)  = 

Apothecaries'  Weight. 
1  Grain 

1  Scruple  (20  grains) 
1  Drachm  (3  scruples)  = 

1  Oz.  (8  drachms)  = 


0-0648  Gramme. 
1  -772  Grammes. 
28-350  Grammes. 
0-45359243  Kilogram. 
6'350  Kilograms. 
12-70  Kilograms. 
50-80  Kilograms. 
0-5080  Quintal. 
/   1-0160  Tonnes  or 
\1016  Kilograms. 

0-0648  Gramme. 

1  -5552  Grammes. 

31 -1035  Grammes. 

0-0648  Gramme. 

1  -296  Grammes. 

3-888  Grammes. 

31-1035  Grammes. 


APOTHECARIES'  MEASURE. 


1  Minim 

1  Fluid  Scruple 

1  Fluid  Drachm  (60  minims) 

1  Fluid  Ounce  (8  drachms) 

1  Pint 


=  0-059  Milliliter. 
=  l-184Milliliters. 
=  3-552  Milliliters. 
=  2-84123  Centiliters. 
=  0'568  Liter. 


1  Gallon  (8  pints  or  160  fluid  oz.)  =  4*5459631  Liters. 


EQUIVALENTS   OF   UNITS   OF  LENGTH          273 


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914402 
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1609-35 
3-20665 


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00189 
27737 


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4-79 


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274     EVOLUTION   OF   WEIGHTS   AND   MEASURES 


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276     EVOLUTION   OF   WEIGHTS   AND   MEASURES 


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r-^      r^H      g 


Decimals 
of  an  inch. 

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COMPARISON   OF   PRICES 


277 


COMPARISON  OF  PRICES. 

FRENCH  AND  GERMAN  PRICES  FOR  METRIC  UNITS,'  BRITISH  PRICES 
FOR  IMPERIAL  UNITS,  AND  UNITED  STATES  PRICES  FOR  UNITED 
STATES  STANDARD  WEIGHTS  AND  MEASURES. 

[Based  upon  the  circular  of  the  Secretary  of  the  Treasury  dated  October  1,  1902, 
fixing  the  legal  equivalent  of  the  (German)  mark  at  23'8  cents,  of  the  (French) 
franc  at  19 '3  cents,  and  the  British  pound  sterling  at  $4 '8665.] 


Franc.       ™f° 
«$£-     ,=. 

Francs       Dollars 
per             per 
meter.          yard. 

Francs     Do^rs 
Uter-   liquid  gal. 

Francs       Dollars 
per             per 
hectoliter,    bushel. 

Shillings     Dollars 
per             per 
British         U.S. 
mp.  gal.  liquid  gal. 

1        =   -088 
2       =  '175 
3        =   '263 
4        =   -350 

1        =  -176 
2        =   -353 
3        =   -529 
4        =  '705 

1        =  -731 
2        =1-461 
3        =2-192 
4        =2-922 

1        =  -068 
2       =  -136 
3       =   -204 
4        =   -272 

1        =  -208 
2       =  -405 
3        =   -608 
4       =  -810 

5        =   -438 
6        =   '525 
7        =   -613 
8        =   '700 
9        =  '788 

5        =   -882 
6        =1-058 
7        =1-234 
8       =1-411 
9        =1-587 

5        =3-653 
6        =4-384 
7        =5-114 
8        =5-844 
9        =6'575 

5       =  -340 
6        =   -408 
7        =   -476 
8        =  -544 
9        =   -612 

5       =1-013 
6       =1-216 
7       =1-418 
8       =1-621 
9        =1-824 

11-423=1 
22-846=2 
34-269  =  3 
45-691=4 

5-667=1 
11-334=2 
17-000=3 
22-667=4 

1-369=1 
2-738=2 
4-106=3 
5-475=4 

14-703=1 
29-407=2 
44-110=3 
58-813=4 

4-935  = 
9-871  = 
14-806  = 
19-742  = 

57-115=5 
68-537=6 
79-960  =  7 
91-383  =  8 
102-806=9 

28-334=5 
34-001  =  6 
39-668=7 
45-334  =  8 
51-001  =  9 

6-844=5 
8-213=6 
9-581=7 
10-950=8 
12-319=9 

73-517=5 
88-220=6 
102-923  =  7 
117-627=8 
132-330  =  9 

24-677= 
29-612  = 
34-548  = 
39-483  = 
44-419  = 

Marks        ™£« 
kilS-an,     ^ufd. 

Marks        Dollars 
per             per 
meter.         yard. 

Marks     Dop»a/8 
liter-    liquid. 

Marks        Dollars 
per             per 
hectoliter,    bushel. 

Shillings      Dollars 
per              per 
British          U.S. 
bus.            bus. 

1        =   -108 
2        =   -216 
3        =   -324 
4        =   -432 

1        =  -218 
2        =  -435 
3        =   -653 
4        =  -871 

1        =   -901 
2        =1-802 
3        =2-730 
4        =3-604 

1        =  -084 
2       =  -168 
3       =  -252 
4       =  -335 

1        =   -236 
2        =  -472 
3        =   -707 
4        =   -943 

5        =   -540 
6        =   '648 
7        =  '756 
8        =   -864 
9        =   '972 

5        =1-088 
6        =1-306 
7        =1-523 
8        =1-741 
9        =1-959 

5        =4-505 
6        =5-406 
7        =6-307 
8        =7-207 
9       =8-108 

5        =   -419 
6        =   -503 
7        =  -587 
8       =  -671 
9       =  -755 

5       =1-179 
6       =1-415 
7       =1-650 
8        =1-886 
9        =2-122 

9-263=1 
18-526=2 
27-789  =  3 
37-052=4 

4-595=1 
9-190  =  2 
13-785=3 
18-380  =  4 

1-110=1 
2-220=2 
3-330=3 
4'440=4 

11-923=1 

23-847=2 
35-770  = 
47-693  = 

4-241=1 
8-483  = 
12-724  = 
16-965  = 

46-316=5 
55-579=6 
64-842  =  7 
74-105=8 
83-368=9 

22-975=5 
27-570=6 
32-165  =  7 
36-760=8 
41-355=9 

5-550=5 
6-660=6 
7-770=7 
8-880=8 
9-990=9 

59-616  = 
71-540  = 
83-463  = 
95-386  = 
107-310  = 

21-207  = 
25-448  = 
29-689  = 
33-931  = 
38-172  = 

278     EVOLUTION   OF   WEIGHTS   AND   MEASURES 


LENGTH. 
INCHES  AND  CENTIMETERS.— EQUIVALENTS  FROM  1  TO  100. 


Inches  to  Centimeters. 

Inches  to  Centimeters. 

Centimeters  to  Inches. 

Centimeters  to  Inches. 

0 

50 

127-000 

0 

50 

19-6850 

1 

2-540 

51 

129-540 

1 

•3937 

51 

20-0787 

2 

5-080 

52 

132-080 

2 

•7874 

52 

20-4724 

3 

7-620 

53 

134-620 

3 

1-1811 

53 

20-8661 

4 

10-160 

54 

137-160 

4 

1-5748 

54 

21-2598 

5 

12-700 

55 

139-700 

5 

1-9685 

55 

21-6535 

6 

15-240 

56 

142-240 

6 

2-3622 

56 

22-0472 

7 

17-780 

57 

144-780 

7 

2-7559 

57 

22-4409 

8 

20-320 

58 

147-320 

8 

3-1496 

58 

22-8346 

9 

22-860 

59 

149-860 

9 

3-5433 

59 

23-2283 

10 

25-4,00 

60 

152-400 

10 

3-9370 

60 

23-6220 

11 

27-940 

61 

154-940 

11 

4-3307 

61 

24-0157 

12 

30-480 

62 

157-480 

12 

4-7244 

62 

24-4094 

13 

33-020 

63 

160-020 

13 

5-1181 

63 

24-8031 

14 

35-560 

64 

162-560 

14 

5-5118 

64 

25-1968 

15 

38-100 

65 

165-100 

15 

5-9055 

65 

25-5905 

16 

40-640 

66 

167-640 

16 

6-2992 

66 

25-9842 

17 

43-180 

67 

170-180 

17 

6-6929 

67 

26-3779 

18 

45-720 

68 

172-720 

18 

7-0866 

68 

26-7716 

19 

48-260 

69 

175-260 

19 

7-4803 

69 

27-1653 

20 

50-800 

70 

177-800 

20 

7-8740 

70 

27-5590 

21 

53-340 

71 

180-340 

21 

8-2677 

71 

27-9527 

22 

55-880 

72 

182-880 

22 

8-6614 

72 

28-3464 

23 

58-420 

73 

185-420 

23 

9-0551 

73 

28-7401 

24 

60-960 

74 

187-960 

24 

9-4488 

74 

29-1338 

25 

63-500 

75 

190-500 

25 

9-8425 

75 

29-5275 

26 

66-040 

76 

193-040 

26 

10-2362 

76 

29-9212 

27 

68-580 

77 

195-580 

27 

10-6299 

77 

30-3149 

28 

71-120 

78 

198-120 

28 

11-0236 

78 

30-7086 

29 

73-660 

79 

200-660 

29 

11-4173 

79 

31-1023 

30 

76-200 

80 

203-200 

30 

11-8110 

80 

31-4960 

31 

78-740 

81 

205-740 

31 

12-2047 

81 

31-8897 

32 

81-280 

82 

208-280 

32 

12-5984 

82 

32-2834 

33 

83-820 

83 

210-820 

33 

12-9921 

83 

32-6771 

34 

86-360 

84 

213-360 

34 

13-3858 

84 

33-0708 

35 

88-900 

85 

215-900 

35 

13-7795 

85 

33-4645 

36 

91-440 

86 

218-440 

36 

14-1732 

86 

33-8582 

37 

93-980 

87 

220-980 

37 

14-5669 

87 

34-2519 

38 

96-520 

88 

223-520 

38 

14-9606 

88 

34-6456 

39 

99-060 

89 

226-060 

39 

15-3543 

89 

35-0393 

40 

101-600 

90 

228-600 

40 

15-7480 

90 

35-4330 

41 

104-140 

91 

231-140 

41 

16-1417 

91 

35-8267 

42 

106-680 

92 

233-680 

42 

16-5354 

92 

36-2204 

43 

109-220 

93 

236-220 

43 

16-9291 

93 

36-6141 

44 

111-760 

94 

238-760 

44 

17-3228 

94 

37-0078 

45 

114-300 

95 

241-300 

45 

17-7165 

95 

37-4015 

46 

116-840 

96 

243-840 

46 

18-1102 

96 

37-7952 

47 

119-380 

97 

246-380 

47 

18-5039 

97 

38-1889 

48 

121  -920 

98 

248-920 

48 

18-8976 

98 

38-5826 

49 

124-460 

99 

251-460 

49 

19-2913 

99 

38-9763 

LENGTH:    FEET   AND   METERS 


279 


LENGTH. 

FEET  AND  METERS.— EQUIVALENTS  FROM  1  TO  100. 


Feet.   Meters. 

Feet.   Meters. 

Meters.    Feet. 

Meters.    Feet. 

0 

50  15-24003 

0 

50  164-04167 

1    -30480 

1  15-54483 

1    3-28083 

1  167-32250 

2    -60960 

2   15-84963 

2    6-56167 

2  170-60333 

3    -91440 

3  16-15443 

3    9-84250 

3  173-88417 

4   1-21920 

4  16-45923 

4   13-12333 

4  177-16500 

5   1-52400 

5   16-76403 

5   16-40417 

5  180-44583 

6   1-82880 

6  17-06883 

6   19-68500 

6  183-72667 

7   2-13360 

7  17-37363 

7   22-96583 

7  187-00750 

8   2-43840 

8  17-67844 

8   26-24667 

8  190-28833 

9   2-74321 

9  17-98324 

9   29-52750 

9  19356917 

10   3-04801 

60  18-28804 

10   32-80833 

60  196-85000 

1   3-35281 

1   18-59284 

1   36-08917 

1  200-13083 

2   3-65761 

2  18-89764 

2   39-37000 

2  203-41167 

3   3-96241 

3  19-20244 

3   42-65083 

3  206-69250 

4   4-26721 

4  19-50724 

4   45-93167 

4  209-97333 

5   4-57201 

5  19-81204 

5   49-21250 

5  21325417 

6   4-87681 

6  20-11684 

6   52-49333 

6  216-53500 

7   5-18161 

7  20-42164 

7   55-77417 

7  219-81583 

8   5-48641 

8  20-72644 

8   59-05500 

8  223-09667 

9   5-79121 

9  21-03124 

9   62-33583 

9  226-37750 

20   6-09601 

70  21-33604 

20   65-61667 

70  229-65833 

1   6-40081 

1  21-64084 

1   68-89750 

1  232-93917 

2   6-70561 

2  21-94564 

2   72-17833 

2  236-22000 

3   7-01041 

3  22-25044 

3   75-45917 

3  239-50083 

4   7-31521 

4  22-55525 

4   78-74000 

4  242-78167 

5   7-62002 

5  22-86005 

5   82-02083 

5  246-06250 

6   7-92482 

6  23-16485 

6   85-30167 

6  249-34333 

7   8-22962 

7  23-46965 

7   88-58250 

7  252-62417 

8   8-53442 

8  23-77445 

8   91  -86333 

8  255-90500 

9   8-83922 

9  24-07925 

9   95-14417 

9  259-18583 

30   9-14402 

80  24-38405 

30   98-42500 

80  262-46667 

1   9-44882 

1  24-68885 

1  101-70583 

1  265-74750 

2   9-75362 

2  24-99365 

2  104-98667 

2  269-02833 

3   10-05842 

3  25-29845 

3  108-26750 

3  272-30917 

4  10-36322 

4  25-60325 

4  111-54833 

4  275-59000 

5  10-66803 

5  25-90805 

5  114-82917 

5  278-87083 

6  10-97282 

6  26-21285 

6  118-11000 

6  282-15167 

7  11-27762 

7  26-51765 

7  121-39083 

7  285-43250 

8  11-58242 

8  26-82245 

8  124-67167 

8  288-71333 

9  11-88722 

9  27-12725 

9  127-95250 

9  291-99417 

40  12-19202 

90  27-43205 

40  131-23333 

90  295-27500 

1   12-49682 

1  27-73686 

1  134-51417 

1  298-55583 

2  12-80163 

2  28-04166 

2  137-79500 

2  301-83667 

3   13-10643 

3  28-34646 

3  141-07583 

3  305-11750 

4  13-41123 

4  28-65126 

4  144-35667 

4  308-39833 

5  13-71603 

5  28-95606 

5  147-63750 

5  311-67917 

6  14-02083 

6  29-26086 

6  150-91833 

6  314-96000 

7  14-32563 

7  29-56566 

7  154-19917 

7  318-24083 

8  14-63043 

8  29-87046 

8  157-48000 

8  321-52167 

9  14-93523 

9  30-17526 

9  160-76083 

9  324-80250 

280     EVOLUTION   OF   WEIGHTS   AND   MEASURES 


LENGTH. 

YARDS  AND  METERS.— EQUIVALENTS  FROM  1  TO  100. 


Yards.   Meters. 

Yards.   Meters. 

Meters.   Yards. 

Meters.   Yards. 

0 

50  45-72009 

0 

50   54-68056 

1    -91440 

51  46-63449 

1   1-09361 

51   55-77417 

2   1-82880 

52   47-54889 

2   2-18722 

52   56-86778 

3   2-74321 

53  48-46330 

3   3-28083 

53   57-96139 

4   3-65761 

54  49-37770 

4   4-37444 

54   59-05500 

5   4-57201 

55   50-29210 

5   5-46806 

55   60-14861 

6   5-48641 

56   51-20650 

6   6-56167 

56   61-24222 

7   6-40081 

57   52-12090 

7   7-65528 

57   62-33583 

8   7-31521 

58  53-03530 

8   8-74889 

58   6342944 

9   8'22962 

59   53-94971 

9   9-84250 

59   64-52306 

10   9-14402 

60  54-86411 

10  10-93611 

60   65-61667 

11   10-05842 

61  55-77851 

11   12-02972 

61   66-71028 

12   10-97282 

62  56-69291 

12  13-12333 

62   67  -80389 

13   11-88722 

63  5760731 

13   14-21694 

63   68-89750 

14   12-80163 

64  58-52172 

14   15-31056 

64   69-99111 

15   13-71603 

65  59-43612 

15   16-40417 

65   71-08472 

16   14-63043 

66   60-35052 

16  17-49778 

66   72-17833 

17   15-54483 

67   61-26492 

17   18-92139 

67   73-27194 

18   16-45923 

68  62-17932 

18   19-68500 

68   74-36556 

19  17-37363 

69   63-09372 

19  20-77861 

69   75-45917 

20  18-28804 

70  64-00813 

20  21-87222 

70   76-55278 

21   19-20244 

71   64-92253 

21  22-96583 

71   77-64639 

22   20-11684 

72  65-83693 

22   24-05944 

72   78-74000 

23   21-03124 

73  66-75133 

23   25-15306 

73   79-83361 

24   21-94564 

74  67-66573 

24  26-24667 

74   80-92722 

25   22-86005 

75   68-58014 

25  27-34028 

75   82-02083 

26   23-77445 

76   69-49454 

26   28-43389 

76   83-11444 

27   24-68885 

77   70-40894 

27   29-52750 

77   84-20806 

28  25-60325 

78   71-32334 

28   30-62111 

78   85-30167 

29  26-51765 

79  72-23774 

29   31-71472 

79   86-39528 

30  27-43205 

80  73-15214 

30  32-80833 

80   87-48889 

31  28-34646 

81  74-06655 

31  33-90194 

81   88-58250 

32  29-26086 

82   74-98095 

32  34-99556 

82   89-67611 

33   30-17526 

83  75-89535 

33  36-08917 

83   90-76972 

34  31-08966 

84   76-80975 

34  37-18278 

84   91-86333 

35  32-00406 

85   77-72415 

35   38-27639 

85   92-95694 

36  32-91846 

86  78-63855 

36   39-37000 

86   94-05056 

37  33-83287 

87   79-55296 

37   40-46361 

87   95-14417 

38   34-74727 

88  80-46736 

38   41  -55722 

88   96-23778 

39   35-66167 

89  81-38176 

39   42-65083 

89   97-33139 

40  36-57607 

90  82-29616 

40  43-74444 

90   98-42500 

41  37-49047 

91  83-21056 

41  44-83806 

91   99-51861 

42   38-40488 

92   84-12497 

42   45-93167 

92  100-61222 

43  39-31928 

93  85-03937 

43   47-02528 

93  101-70583 

44  40-23368 

94  85-95377 

44  48-11889 

94  102-79944 

45   41-14808 

95   86-86817 

45   49-21250 

95  103-89306 

46   42-06248 

96  87-78257 

46   50-30611 

96  104-98667 

47   42-97688 

97  88-69697 

47   51-39972 

97  106-08028 

48  43-89129 

98  89-61138 

48   52-49333 

98  107-17389 

49  44-80569 

99   90-52578 

49  53-58694 

99  108-26750 

LENGTH:    MILES   AND  KILOMETERS 


281 


LENGTH. 

MILES  AND  KILOMETERS.— EQUIVALENTS  FROM  1  TO  100. 


Miles.  Kilometers. 

Miles.   Kilometers. 

Kilometers.  Miles. 

Kilometers.  Miles. 

0 

50   80-4674 

0 

50  31-06850 

1   1-6093 

1   82-0767 

1    -62137 

1  31-68987 

2   3-2187 

2   83-6861 

2   1-24274 

2  32-31124 

3   4-8280 

3   85-2954 

3   1-86411 

3  32-93261 

4   6-4374 

4   86-9047 

4   2-48548 

4  33-55398 

5   8-0467 

5   88-5141 

5   3-10685 

5  34-17535 

6   9-6561 

6   90-1234 

6   3-72822 

6  34-79672 

7   11-2654 

7   91-7328 

7   4-34959 

7  35-41809 

8  12-8748 

8   93-3421 

8   4-97096 

8  36-03946 

9   14-4841 

9   94-9515 

9   5-59233 

9  36-66083 

10  16-0935 

60   96-5608 

10   6-21370 

60  37-2822O 

1  17-7028 

1   98-1702 

1   6-83507 

1  37-90357 

2  19-3122 

2   99-7795 

2   7*45644 

2  38-52494 

3  20-9215 

3  101  -3889 

3   8-07781 

3  39-14631 

4  22-5309 

4  102-9982 

4   8-69918 

4  39-76768 

5  24-1402 

5  104-6076 

5   9-32055 

5  40-38905 

6  25-7496 

6  106-2169 

6   9-94192 

6  41-01042 

7  27-3589 

7  107-8263 

7  10-56329 

7  41-63179 

8  28-9682 

8  109-4356 

8  11-18466 

8  42-25316- 

9  30-5776 

9   111-0450 

9  11-80603 

9  42-87453 

20  32-1869 

70  112-6543 

20  12-42740 

70  43-49590 

1  33-7963 

1  114-2637 

1  13-04877 

1  44-11727 

2  35-4056 

2  115-8730 

2  13-67014 

2  44-73864 

3  37-0150 

3  117-4823 

3  14-29151 

3  45-36001 

4  38-6243 

4  119-0917 

4   14-91288 

4  45-98138 

5  40-2337 

5  120-7010 

5   15-53425 

5  46-60275 

6  41  -8430 

6   122-3104 

6  16-15562 

6  47-22412 

7  43-4524 

7   123-9197 

7  16-77699 

7  47-84549 

8  45-0617 

8   125-5291 

8  17-39836 

8  48-46686 

9  46-6711 

9  127-1384 

9  18-01973 

9  49-08823 

30  48-2804 

80  128-7478 

30  18-64110 

80  49-70960 

1  49-8898 

1  130-3571 

1  19-26247 

1  50-33097 

2  51-4991 

2  131-9665 

2  19-88384 

2  50-95234 

3  53-1085 

3  133-5758 

3  20-50521 

3  51-57371 

4  54-7178 

4  135-1852 

4  21-12658 

4  52-19508 

5  56-3272 

5  136-7945 

5  21-74795 

5  52-81<)45 

6  57-9365 

6  138-4039 

6  22-36932 

6  53-43782 

7  59-5458 

7  140-0132 

7  22-99069 

7  54-05919 

8  61-1552 

8   141-6226 

8  23-61206 

8  54-68056 

9  62-7645 

9   143-2319 

9  24-23343 

9  55-30193 

40  64-3739 

90  144-8412 

40  24-85480 

90  55-92330 

1  65-9832 

1  146-4506 

1  25-47617 

1  56-54467 

2  67-5926 

2  148-0599 

2  26-09754 

2  57-16604 

3  69-2019 

3  149-6693 

3  26-71891 

3  57-78741 

4  70-8113 

4  151-2786 

4  27-34028 

4  58-40878 

5  72-4206 

5   152-8880 

5  27-96165 

5  59-03015 

6   74-0300 

6   154-4973 

6  28-58302 

6  59-65152 

7   75-6393 

7   156-1067 

7  29-20439 

7  60-27289 

8  77-2487 

8  157-7160 

8  29-82576 

8  60-89426 

9  78-8580 

9  159-3254 

9  30-44713 

9  61-51562 

282     EVOLUTION   OF   WEIGHTS   AND   MEASURES 


AREAS. 
ACRES  AND  HECTARES.— EQUIVALENTS  FROM  1  TO  100. 


Acres.   Hectares. 

Acres.   Hectares. 

Hectares.   Acres. 

Hectares.   Acres. 

0 

50  20-23436 

0 

50  123-55220 

1   0-40469 

1  20-63905 

1    2-47104 

1   126-02324 

2   0-80937 

2  21-04374 

2    4-94209 

2   128-49428 

3   1-21406 

3   21-44842 

3    7-41313 

3   130-96533 

4   1-61875 

4  21-85311 

4    9-88418 

4  133-43637 

5   2-02344 

5  22-25780 

5   12-35522 

5  135-90742 

6   2-42812 

6  22-66249 

6   14-82626 

6  138-37846 

7   2-83281 

7  23-06717 

7   17-29731 

7  140-84950 

8   3-23750 

8  23-47186 

8   19-76835 

8  143-32055 

9   3-64219 

9  23-87655 

9   22-23940 

9   145-79159 

10   4-04687 

60  24-28124 

10   24-71044 

60  148-26264 

1   4-45156 

1  24-68592 

1   27-18148 

1   150-73368 

2   4-85625 

2  25-09061 

2   29-65253 

2  153-20472 

3   5-26093 

3  25-49530 

3   32-12357 

3  155-67577 

4   5-66562 

4  25-89998 

4   34-59462 

4  158-14681 

5   6-07031 

5  26-30467 

5   37-06566 

5  160-61786 

6   6-47500 

6  26-70936 

6   39-53670 

6   163-08890 

7   6-87968 

7  27-11405 

7   42-00775 

7   165-55994 

8   7-28437 

8  27-51873 

8   44-47879 

8  168-03099 

9   7-68906 

9  27-92342 

9   46-94983 

9   170-50203 

20   8-09375 

70  28-32811 

20   49-42088 

70  172-97308 

1   8-49843 

1  28-73280 

1   51-89192 

1  175-44412 

2   8-90312 

2  29-13748 

2   54-36297 

2  177-91516 

3   9-30781 

3  29-54217 

3   56-83401 

3  180-38621 

4   9-71249 

4  29-94686 

4   59-30505 

4  182-85725 

5  10-11718 

5  30-35154 

5   61-77610 

5   185-32829 

6   10-52187 

6  30-75623 

6   64-24714 

6  187-79934 

7  10-92656 

7  31-16092 

7   66-71819 

7  190-27038 

8  11-33124 

8  31-56561 

8   69-18923 

8   192-74143 

9  11-73593 

9  31-97029 

9   71-66027 

9   195-21247 

30  12-14062 

80  32-37498 

30   74-13132 

80  197-68351 

1   12-54531 

1  32-77967 

1   76-60236 

1  200-15456 

2  12-94999 

2  33-18436 

2   79-07341 

2  202-62560 

3  13-35468 

3  33-58904 

3   81-54445 

3  205-09665 

4  13-75937 

4  33-99373 

4   84-01549 

4  207-56769 

5   14-16405 

5  34-39842 

5   86-48654 

5  210-03873 

6  14-56874 

6  34-80310 

6   88-95758 

6  212-50978 

7  14-97343 

7  35-20779 

7   91-42863 

7  214-98082 

8  15-37812 

8  35-61248 

8   93-89967 

8  217-45187 

9  15-78280 

9  36-01717 

9   96-37071 

9  219-92291 

40  16-18749 

90  36-42185 

40   98-84176 

90  222-39395 

1  16-59218 

1  36-82654 

1  101  -31280 

1  224-86500 

2  16*99686 

2  37-23123 

2  103-78385 

2  227-33604 

3  17-40155 

3  37-63592 

3  106-25489 

3  229-80709 

4  17-80624 

4  38-04060 

4  108-72593 

4  232-27813 

5  18-21093 

5  38-44529 

5  111-19698 

5  234-74917 

6   18-61561 

6  38-84998 

6   113-66802 

6  237-22022 

7  19-02030 

7  39-25466 

7  116-13906 

7  239-69126 

8  19-42499 

8  39-65935 

8  118-61011 

8  242-16231 

9   19-82968 

9  40-06404 

9  121-08115 

9  244-63335 

CAPACITY  :  LIQUID   QUARTS   TO   LITERS       283 

CAPACITY. 
LIQUID  QUARTS  TO  LITERS.— EQUIVALENTS   FROM  1  TO  100. 


Quarts.   Liters. 

Quarts.   Liters. 

Liters.   Quarts. 

Liters.  Quarts. 

0 

50  47-31793 

0 

50   52-83409 

1    -94636 

1  48-26429 

1   1-05668 

1   53-89077 

2   1-89272 

2  49-21065 

2   2-11336 

2   54-94746 

3   2-83908 

3  50-15701 

3   3-17005 

3   56-00414 

4   3-78543 

4  51-10337 

4   4-22673 

4   57-06082 

5   4-73179 

5  52-04972 

5   5-28341 

5   58-11750 

6   5-67815 

6  52-99608 

6   6-34009 

6   59-17418 

7   6-62451 

7  53-94244 

7   7-39677 

7   60-23086 

8   7-57087 

8  54-88880 

8   8-45345 

8   61  -28755 

9   8-51723 

9  55-83516 

9   9-51014 

9   62-34423 

10   9-46359 

60  56-78152 

10  10-56682 

60   63-40091 

1   10-40994 

1  57-72788 

1   11-62350 

1   64-45759 

2  1  1  -35630 

2  58-67423 

2   12-68018 

2   65-51428 

3   12-30266 

3  59-62059 

3   13-73686 

3   66-57096 

4  13-24902 

4  60-56695 

4  14-79355 

4   67-62764 

5   14-19538 

5  61-51331 

5  15-85023 

5   68-68432 

6   15-14174 

6  62-45967 

6  16-90691 

6   69-74100 

7   16-08810 

7  63-40603 

7  17-96359 

7   70-79768 

8   17-03446 

8  64-35239 

8  19-02027 

8   71-85437 

9   17-98081 

9  65-29875 

9  20-07696 

9   72-91105 

20  18-92717 

70  66-24510 

20  21-13364 

70   73-96773 

1  19-87353 

1  67-19146 

1  22-19032 

1   75-02441 

2  20-81989 

2  68-13782 

2  23-24700 

2   76-08109 

3  21-76625 

3  69-08418 

3  24-30368 

3   77-13778 

4  22-71261 

4  70-03054 

4  25-36036 

4   78-19446 

5  23-65897 

5  70-97690 

5  26-41705 

5   79-25114 

6  24-60532 

6  71-92326 

6  27-47373 

6   80-30782 

7  25-55168 

7  72-86961 

7  28-53041 

7   81-36450 

8  26-49804 

8  73-81597 

8  29-58709 

8   82-42119 

9  27-44440 

9  74-76233 

9  30-64377 

9   83-47787 

30  28-39076 

80  75-70869 

30  31-70046 

80   84-53455 

1  29-33712 

1  76-65505 

1  32-75714 

1   85-59123 

2  30-28348 

2  77-60141 

2  33-81382 

2   86-64791 

3  31-22983 

3  78-54777 

3  34-87050 

3   87'70459 

4  32-17619 

4  79-49412 

4  35-92718 

4   88-76128 

5  33-12255 

5  80-44048 

5  36-98387 

5   89-81796 

6  34-06891 

6  81-38684 

6  38-04055 

6   90-87464 

7  35-01527 

7  82-33320 

7  39-09723 

7   91-93132 

8  35-96163 

8  83-27956 

8  40-15391 

8   92-98800 

9  36-90799 

9  84-22592 

9  41-21059 

9   94-04469 

40  37-85436 

90  85-17228 

40  42-26727 

90   95-10137 

1  38-80070 

1  86-11863 

1  43-32396 

1   96-15805 

2  39-74706 

2  87-06499 

2  44-38064 

2   97-21473 

3  40-69342 

3  88-01135 

3  45-43732 

3   98-27141 

4  41-63978 

4  88-95771 

4  46-49400 

4   99-32809 

5  42-58614 

5  89-90407 

5  47-55068 

5  100-38478 

6  43-53250 

6  90-85043 

6  48-60737 

6  101-44146 

7  44-47886 

7  91-79679 

7  49-66405 

7  102-49814 

8  45-42521 

8  92-74315 

8  50-72073 

8  103-55482 

9   46-37157 

9  93-68950 

9  51-77741 

9   104-61150 

284     EVOLUTION   OF   WEIGHTS   AND   MEASURES 


CAPACITY. 
GALLONS  AND  LITERS.— EQUIVALENTS  FROM  1  TO  100. 


Gallons.   Liters. 

Gallons.   Liters. 

Liters.   Gallons. 

Liters.   Gallons. 

0 

50  1892717 

0 

50  13-20852 

1    37854 

1  193-0572 

1    -26417 

1   13-47269 

2    7-5709 

2  196-8426 

2    -52834 

2   13-73686 

3   11-3563 

3  200-6280 

3    -79251 

3   14-00103 

4   15-1417 

4  204-4135 

4   1  -05668 

4   14-26521 

5   18-9272 

5  208-1989 

5   1-32085 

5  14-52938 

6   22-7126 

6   211-9843 

6   1  -58502 

6   14-79355 

7   26-4980 

7  215-7698 

7   1-84919 

7  15-05772 

8   30-2835 

8  219-5552 

8   2-11336 

8  15-32189 

9   34-0689 

9  223-3406 

9   2-37753 

9  15-58606 

10   37-8543 

60  227-1261 

10   2-64170 

60  15-85023 

1   41  -6398 

1  230-9115 

1   2-90588 

1   16-11440 

2   45-4252 

2  234-6969 

2   3-17005 

2  16-37857 

3   49-2106 

3  238-4824 

3   3-43422 

3  16-64274 

4   52-9961 

4  242-2678 

4   3-69839 

4  16-90691 

5   56-7815 

5  246  -0532 

5   3-96256 

5  17-17108 

6   60-5670 

6  249-8387 

6   4-22673 

6   17-43525 

7   64-3524 

7  253-6241 

7   4-49090 

7'  17-69942 

8   68-1378 

8  257-4095 

8   4-75507 

8   17-96359 

9   71-9233 

9  261-1950 

9   5-01924 

9  18-22776 

20   75-7087 

70  264-9804 

20   5-28341 

70  18-49193 

1   79-4941 

1  268-7658 

1   5-54758 

1   18-75610 

2   83-2796 

2  272-5513 

2   5-81175 

2  19-02027 

3   87-0650 

3  276-3367 

3   6-07592 

3   19-28444 

4   90-8504 

4  280-1222 

4   6-34009 

4   19-54861 

5   94-6359 

5  283-9076 

5   6-60426 

5   19-81279 

6   98-4213 

6  287*6930 

6   6-86843 

6  20-07696 

7   102-2067 

7  291-4785 

7   7-13260 

7  20-34113 

8  105-9922 

8  295-2639 

8   7-39677 

8  20-60530 

9  109-7776 

9  299-0493 

9   7-66094 

9  20-86947 

30  113-5630 

80  302-8348 

30   7-92511 

80  21-13364 

1  117-3485 

1  306-6202 

1   8-18928 

1  21  -39781 

2  121-1339 

2  310-4056 

2   8-45345 

2  21-66198 

3  124-9193 

3  314-1911 

3   8-71763 

3  21  -92615 

4  128-7048 

4  317-9765 

4   8-98180 

4  22-19032 

5  132-4902 

5  321-7619 

5   9-24597 

5  22-45449 

6   136-2756 

6  325-5474 

6   9-51014 

6  22-71866 

7  140-0611 

7  329-3328 

7   9-77431 

7  22-98283 

8  143-8465 

8  333-1182 

8   10-03848 

8  23-24700 

9   147-6319 

9  336-9037 

9  10-30265 

9  23-51117 

40  151-4174 

90  340-6891 

40  10-56682 

90  23-77534 

1  155-2028 

1  344-4745 

1   10-83099 

1  24-03951 

2  158-9882 

2  348-2600 

2  11-09516 

2  24-30368 

3  162-7737 

3  352-0454 

3  11-35933 

3  24-56785 

4  166-5591 

4  355-8308 

4  11-62350 

4  24-83202 

5  170-3446 

5  359-6163 

5  11-88767 

5  25-09619 

6  174-1300 

6  363-4017 

6  12-15184 

6  25-36036 

7  177-9154 

7  367-1871 

7  12-41601 

7  25-62454 

8  181  -7009 

8  370-9726 

8  12-68018 

8  25-88871 

9  185-4863 

9  374-7580 

9  12-94435 

9  26*15288 

MASSES :  AVOIRDUPOIS  POUND  AND  KILOGRAM  285 


MASSES. 
AVOIRDUPOIS  POUND  &  KILOGRAM.— EQUIVALENTS  FROM  1  TO  100. 


Pounds.    Kilos. 

Pounds.    Kilos. 

Kilos.   Pounds. 

Kilos.   Pounds. 

0 

50  22-67962 

0 

50  110-2311 

1    -45359 

1  23-13321 

1    2-2046 

1  112-4357 

2    -90718 

2  23-58681 

2    4-4092 

2  114-6404 

3   1-36078 

3  24-04040 

3    6-6139 

3   116-8450 

4   1-81437 

4  24-49399 

4    8-8185 

4  119-0496 

5   2-26796 

5  24-94758 

5   11-0231 

5  121-2542 

6   2-72155 

6  25-40118 

6   13-2277 

6  123-4589 

7   3-17515 

7  25-85477 

7   15-4324 

7  125-6635 

8   3-62874 

8  26-30836 

8   17-6370 

8  127-8681 

9   4-08233 

9  26-76195 

9   19-8416 

9  130-0727 

10   4-53592 

60  27-21555 

10   22-0462 

60  132-2773 

1   4-98952 

1  27-66914 

1   24-2508 

1  134-4820 

2   5-44311 

2  28-12273 

2   26-4555 

2  136-6866 

3   5-89670 

3  28-57632 

3   28-6601 

3  138-8912 

4   6-35029 

4  29-02992 

4   30-8647 

4  141-0958 

5   6-80389 

5  29-48351 

5   33-0693 

5  143-3005 

6   7-25748 

6  29-93710 

6   35-2740 

6  145-5051 

7   7-71107 

7  30-39069 

7   37-4786 

7  147-7097 

8   8-16466 

8  30-84429 

8   39-6832 

8  149-9143 

9   8-81826 

9  31-29788 

9   41-8878 

9  152-1189 

20   9-07185 

70  31-75147 

20   44-0924 

70  154-3236 

1   9-52544 

1  32-20506 

1   46-2971 

1  156-5282 

2   9-97903 

2  32-65865 

2   48-5017 

2  158-7328 

3   10-43263 

3  33-11225 

3   50-7063 

3  160-9374 

4  10-88622 

4   33-56584 

4   52-9109 

4  163-1421 

5  11-33981 

5  34-01943 

5   55-1156 

5  165-3467 

6   11-79340 

6  34-47302 

6   57-3202 

6  167-5513 

7  12-24700 

7  34-92662 

7   59-5248 

7  169-7559 

8   12-70059 

8  35-33021 

8   61-7294 

8  171-9605 

9   13-15418 

9  35-83380 

9   63-9340 

9  174-1652 

30  13-60777 

80  36-28739 

30   66-1387 

80  176-3698 

1  14-06137 

1  36-74099 

1   68-3433 

1   178-5744 

2   14-51496 

2  37-19458 

2   70-5479 

2  180-7790 

3   14-96855 

3  37-64817 

3   72-7525 

3  182-9837 

4  15-42214 

4  38-10176 

4   74-9572 

4  185-1883 

5  15-87573 

5  38-55586 

5   77-1618 

5  187-3929 

6  16-32933 

6  39-00895 

6   79-3664 

6  189-5975 

7   16-78292 

7  39-46254 

7   81-5710 

7  191-8021 

8  1723651 

8  39-91613 

8   83-7756 

8  194-0068 

9  17-69010 

9  40-36973 

9   85-9803 

9  196-2011 

40  18-14370 

90  40-82332 

40   88'1849 

90  198-4160 

1  18-59729 

1  41-27691 

1   90-3895 

1  200-6206 

2  19-05088 

2  41-73050 

2   92-5941 

2  202-8253 

3  19-50447 

3  42-18410 

3   94-7988 

205-0299 

4  19-95807 

4  42-63769 

4   97-0034 

207-2345 

5  20-41166 

5  43-09128 

5   99-2080 

209-4391 

6  20-86525 

6  43-54487 

6   101-4126 

211-6437 

7  21-31884 

7  43-99847 

7   103-6172 

213-8484 

8  21  -77244 

8  44-45206 

8   105-8219 

216-0530 

9  22-22603 

9  44-90565 

9  108-0265 

218-2576 

286     EVOLUTION   OF   WEIGHTS   AND   MEASURES 


COMPARISON   OF   THE   VARIOUS   TONS   AND    POUNDS 
IN   USE   IN   THE  UNITED   STATES. 

FROM  1  TO  10  UNITS. 


LONG  TONS. 

SHORT  TONS. 

METRIC  TONS. 

KILOGRAMS. 

AVOIRDUPOIS 
POUNDS. 

TROY  POUNDS. 

•00036735 

•00041143 

•00037324 

•37324 

•822857 

1 

•00044643 

•00050000 

•00045359 

•45359 

1 

1-21528 

•00073469 

•00082286 

•00074648 

•74648 

1-64571 

2 

•00089286 

•00100000 

•00090718 

•90718 

2 

2-43056 

•00098421 

•00110231 

•00100000 

1 

2-20462 

2-67923 

•00110204 

•00123429 

•00111973 

1-11973 

2-46857 

3 

•00133929 

•00150000 

•00136078 

1-36078 

3 

3-64583 

•00146939 

•00164571 

•00149297 

1-49297 

3-29143 

4 

•00178571 

•00200000 

•00181437 

1-81437 

4 

4-86111 

•00183673 

•00205714 

•00186621 

1-86621 

4-11429 

5 

•00196841 

•00220462 

•00200000 

2 

4-40924 

5-35846 

•00220408 

•00246857 

•00223945 

2-23945 

4-93714 

6 

•00223214 

•00250000 

•00226796 

2-26796 

5 

6-07639 

•00257143 

•00288000 

•00261269 

2-61269 

5-76000 

7 

•00267857 

•00300000 

•00272155 

2-72155 

6 

7-29167 

•00293878 

•00329143 

•00298593 

2-98593 

6-58286 

8 

•00295262 

•00330693 

•00300000 

3 

6-61387 

8-03769 

•00312500 

•00350000 

•00317515 

3-17515 

7 

8-50694 

•00330612 

•00370286 

•00335918 

3-35918 

7-40571 

9 

•00357143 

•00400000 

•00362874 

3-62874 

8 

9-72222 

•00393683 

•00440924 

•00400000 

4 

8-81849 

10-71691 

•00401786 

•00450000 

•00408233 

4-08233 

9 

10-93750 

•00492103 

•00551156 

•00500000 

5 

11-0231 

13-39614 

•00590524 

•00661387 

•00600000 

6 

13-2277 

16-07537 

•006S8944 

•00771618 

•00780000 

7 

15-4324 

18-75460 

•00787365 

•00881849 

•00800000 

8 

17-6370 

21-43383 

•00885786 

•00992080 

•0090000 

9 

19-8416 

24-11306 

•89287 

1 

•90718 

907-18 

2,000-00 

2,430-56 

•98421 

1-10231 

1 

1,000-00 

2,204-62 

2,679-23 

1 

1-12000 

1-01605 

1,016-05 

2,240-00 

2,722-22 

1-78571 

2 

1-81437 

1,814-37 

4,000-00 

4,861'H 

1-96841 

2-20462 

2 

2,000-00 

4,409-24 

5,358-46 

2 

2-24000 

2-03209 

2,032-09 

4,480-00 

5,444-44 

2-67857 

3 

2-72155 

2,721  -55 

6,000-00 

7,291-67 

2-95262 

3-30693 

3 

3,000-00 

6,613-87 

8,037-69 

3 

3-36000 

3-04814 

3,048-14 

6,720-00 

8,166-67 

3-57143 

4 

3-62874 

3,628-74 

8,000-00 

9,722-22 

3-93683 

4-40924 

4 

4,000-00 

8,818-49 

10,716-91 

4 

4-48000 

4-06419 

4,064-19 

8,960-00 

10,888-89 

4-46429 

5 

4-53592 

4,535-92 

10,000-00 

12,152-78 

4-92103 

5-51156 

5 

5,000-00 

11,023-11 

13,396-14 

5 

5-60000 

5-08024 

5,080-24 

11,200-00 

13,611-11 

5-35714 

6 

5-44311 

5,443-11 

12,000-00 

14,583-33 

5-90524 

6-61387 

6 

6,000-00 

13,227-73 

16,075-37 

6 

6-72000 

6-09628 

6,096-28 

13,440-00 

16,333-33 

6-25000 

7 

6-35029 

6,350-29 

14,000-00 

17,013-89 

6-88944 

7-71618 

7 

7,000-00 

15,432-36 

18,754-60 

7 

7-84000 

7-11232 

7,112-32 

15,680-00 

19,055-56 

7-14286 

8 

7-25748 

7,257*48 

16,000-00 

19,444-44 

7-87365 

8-81849 

8 

8.000-00 

17,636-98 

21,433-83 

8 

8-96000 

8-12838 

8,128-38 

17,920-00 

21,777-78 

8-03571 

9 

8-16466 

8,164-66 

18,000-00 

21,875-00 

8-85786 

9-92080 

9 

9,000-00 

19,841-60 

24,113-06 

9 

10-08000 

9-14442 

9,144-42 

20,160-00 

24,500-00 

MEASURES   OF   CAPACITY 


287 


MEASURES  OF  CAPACITY. 
EQUIVALENTS  FROM  1  TO  10. 


Milli-         U.S. 

Milli-      AU0the. 

u.s.       MiU. 

U.S. 

U.S. 

liters.       Liquid 
(c.c.)      Ounces. 

(c*c*)        Drams. 

Scruples.      (c*c>) 

Liquid       Liters. 
Quarts. 

Liquid       Liters. 
Gallons. 

1        =0*03381 

1          =0*2705 

0*8115=  1 

1            =0-94636 

0-26417=  1 

2        =0*06763 

2          =0*5410 

1          =  1-2322 

1-05668=1 

0*52834=  2 

3        =0*10144 

3         =0-8115 

1*6231=  2 

2           =1-89272 

0*79251=  3 

4        =0*13526 

3-6967=1 

2          =  2-4645 

2*11336=2 

1            =  3*78548 

2*4346=  3 

5        =0-16907 

4         =1-0820 

3           =2*83908 

1*05668=  4 

6        =0-20288 

5          =1*3525 

3*2461=  4 

3*17005=3 

1*32085=  5 

7        =0-23670 

6          =1-6231 

4           =3-78543 

1*58502=  6 

8        =0-27051 

7         =1*8936 

4          =  4'9290 

4-22673=4 

1*84919=  7 

9        =0-30432 

7-3934=2 

4*0577=  5 
4*8692=  6 

5           =4-73179 

2           =  7*57087 

5          =  6-1612 

29-574=1 

8          =2*1641 

5-6807=  7 

5-28341=5 

2-11336=  8 

59-147=2 

9          =2-4346 

6         =  7*3934 

6           =5-67815 

2*37753=  9 

88-721=3 

11-0901  =  3 

6*4923=  8 

6-34009=6 

3           =11-35630 

118-295=4 

14-7869=4 

7          =  8*6257 

7           =6-62451 

4           =15*14174 

147-869=5 

18-4836=5 

7*3038=  9 

7-39677=7 

=  18*92717 

177-442=6 

22-1803=6 

8         =  9*8579 

8           =7-57088 

=  22*71261 

207-016  =  7 

25-8770=7 

9         =11*0901 

8-45345=8 

=  26*49804 

236-590=8 

29-5737=8 

9            =8-51723 

=  30-28348 

266-163  =  9 

33-2704=9 

9-51014=9 

=  34*06891 

U.S. 
Dry          Liters. 
Quarts. 

Pack's.        Liters- 

Deka-          U.S. 
liters.        Pecks. 

U.S.         Hecto- 
Buehels.       liters. 

U.S.     Hectolitres 
Bushels         per 
per  Acre.    Hectare. 

0-9081=1 

0*11351=  1 

0*8810=  1 

1           =0-35239 

1           =0*87078 

1          =1-1012 

0*22702=  2 

1         =  1*1351 

2           =0-70479 

1*14840=1 

1-8162=2 

0*34053=  3 

1-7620=  2 

2-83774=1 

2            =1*74156 

2          =2-2025 

0*45404=  4 

2         =  2-2702 

3           =1*05718 

2*29680=2 

2-7242  =  3 

0*56755=  5 

2-6429=  3 

4           =1-40957 

3           =2*61233 

3         =3*3037 

0*68106=  6 

3          =  3-4053 

5           =1*76196 

3-44519=3 

3*6323=4 

0*79457=  7 

3-5239=  4 

5*67548=2 

4           =3*48311 

4          =4*4049 

0*90808=  8 

4          =  4-5404 

6            =2*11436 

4*59359=4 

4-5404  =  5 

1            =  8*80982 

4-4049=  5 

7           =2-46675 

5            =4-35389 

5          =5-5061 

5          =  5-6755 

5*4485  =  6 

5-2859=  6 

6         =6-6074 

1*02157=  9 

6          =  6-8106 

8           =2-81914 

5-74199=5 

6-3565=7 
7         =7-7086 
7-2646=8 

2           =17-61964 
3            =26*42946 
4           =35-23928 

6-1669=  7 
7         =  7-9457 
7-0479=  8 

8-51323=3 
9           =3-17154 
11-35097=4 

6           =5-22467 
6-89039=6 
7           =6-09545 

8          =8-8098 

5            =44-04910 

7*9288=  9 

14-18871=5 

8            =6-96622 

8-1727=9 

6            =52*85892 

8         =  9*0808 

17*02645=6 

8-03879=7 

9         =9-9110 

7           =61*66874 

9         =10-2159 

19-86420=7 

9            =7-83700 

8            =70*47856 

22*70194=8 

9-18719=8 

9            =79-28838 

25*53968=9 

10-33558=9 

288     EVOLUTION   OF   WEIGHTS   AND   MEASURES 


MEASUEES  OF  MASS. 
EQUIVALENTS  FROM  1  TO  10. 


Grains.      Grams. 

Avoir- 
dupois      Grams. 
Ounces. 

oS,    a™-- 

Avoir-         TZ-., 

£2±  <£-• 

Troy          Kilo- 
Pounds,      grams. 

1          =0-06480 

0-03527=     1 

0-03215=     1 

1            =0-45359 

1           =0-37324 

2         =0-12960 

0-07055=     2 

0-06430=     2 

2           =0-90718 

2            =0-74648 

3          =0-19440 

0-10582=     3 

0-09645=     3 

2-20462=1 

2-67923  =  1 

4          =0-25920 

0-14110=     4 

0-12860=     4 

3           =1-36078 

3            =1-11973 

5          =0-32399 

0-17637=     5 

0-16075=     5 

4           =1-81437 

4           =1-49297 

6          =0-38879 

0-21164=     6 

0-19290=     6 

4-40924=2 

5           =1-86621 

7          =0-45359 

0-24692=     7 

0-22506=     7 

5           =2-26796 

5-35846  =  2 

8          =0-51839 

0-28219=     8 

0-25721=     8 

6           =2-72155 

6            =2-23945 

9          =0-58319 

0-31747=     9 

0-28936=     9 

6-61387=3 

7            =2-61269 

15-4324=1 

1            =  28-3495 

1            =  31-10348 

7           =3-17515 

8            =2-98593 

30-8647=2 

2            =  56-6991 

2            =  62-20696 

8           =3-62874 

8-03769=3 

46-2971=3 

3            =  85-0486 

3            =  93-31044 

8-81849=4 

9           =3-35918 

61-7294=4 

4            =113-3981 

4            =124-41392 

9            =4-08233 

10-71691=4 

77-1618=5 

5            =141-7476 

5            =155-51740 

11-02311=5 

13-39614=5 

92-5941=6 

6           =170-0972 

6            =186-62088 

13-22773=6 

16-07537=6 

108-0265=7 

7            =198-4467 

7           =217-72437 

15-43236=7 

18-75460=7 

123-4589=8 

8           =226-7962 

8            =248-82785 

17-63698=8 

21-43383=8 

138-8912=9 

9           =255-1457 

9           =279-93133 

19-84160=9 

24-11306  =  9 

APOTHECARIES'   AND   METRIC  WEIGHT        289 


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290     EVOLUTION   OF   WEIGHTS   AND   MEASURES 


TABLE   GIVING 
DENSITY   (SPECIFIC   GRAVITY),   MELTING  POINT 

AND  BOILING  POINT 
MISCELLANEOUS  ELEMENTS  AND  SOLIDS. 


Density. 

Melting  Point. 
Centigrade. 

Boiling  Point. 
Centigrade. 

Aluminium         - 

2-60—  (270) 

600-850 

Amber       -         -         -         - 

1-078 

Antimony  ..... 

6-71 

425—450 

1400—1700 

Asbestos    

2-0-2-8 

Asphaltum         - 

1-07—1-2 

Bismuth     

9-8 

267—268 

1400—1700 

Bone 

1-7—2-0 

Brass 

8-1—8-6 

900—920 

Bronze        -         -         -         - 

8-7 

Butter        

0-86 

31—31-5 

Cadmium  -         -         -         -    '    • 

8-6 

315—320 

760-770 

Calcite       -         -         -         -        » 

•2-7 

Chalk         -         -         -         -     '    - 

2-25—2-69 

Cobalt        -         -         -         -        - 

8-6 

1500—1800 

Constantan         - 

8-8 

Copper 
Cork  

8-5—8-9 
0-2 

1000—1150 

Feldspar    

2-55 

German  silver  - 

8-5 

1000 

Glass,  common  - 
,,       plate,  crown  - 
„       flint,  light       -         ... 
,,          ,,      heavy     - 

2-50—2-70 
2-45—2-72 
3-15—3-4 
3-6-3-9 

}         800 
to 
|        1400 

Gold  

19-2—19-3 

1065 

Granite       

2-5—2-9 

Graphite    

1-8—2-24 

Gutta  percha     - 

0-96—0-98 

Gypsum     

2-32 

Ice     

0-9167 

0 

100 

Iron,  cast  

7-1—7-7 

1200—1400 

,,      wrought  .... 

7-8 

,,      wire          .... 

7-7 

,,      cast  steel 

7'8 

1300—1400 

Ivory 

1-9 

Lard  ....         . 

0-93 

41—42 

Lead  

11-3 

325—327 

1450—1600 

Lime,  burned    -         ... 

2-3-3-2 

Magnesium         .... 

1-7 

630 

About  1100 

Manganese         .... 

7-4 

1900? 

Manganin  - 

8-4 

Marble       

2-65-2-8 

Mica  

2-65—2-93 

Nickel        

8-8-8-9 

1450—1600 

Paraffin      

0-87 

38—56 

350—430 

Platinum    

21-4—21-5 

1800 

Porcelain   

2-2—2-5 

Potassium  

0-87 

62 

687—731 

Quartz        ..... 

2-65 

2000 

Rubber,  unvulcanised 

0-92-0-95 

,,         hard     .... 

1-2 

MISCELLANEOUS   ELEMENTS   AND   SOLIDS      291 

MISCELLANEOUS   ELEMENTS   AND   SOLIDS— Continued. 


Density. 

Melting  Point. 
Centigrade. 

Boiling  Point. 
Centigrade. 

Sandstone  

2-2—2-5 

Serpentine          .... 

2-4-2-7 

Silver         

10-5 

960 

Slate-        ..... 

2-6-27 

Sodium       

0-98 

95-6—97-6 

740 

Spermaceti          .... 

0-88—0-94 

44 

Sulphur      

2-07 

114 

448 

Tallow,  beef      - 

0-97 

43 

,,         mutton 

0-92 

47—50 

Tin     

7-3 

227—232 

1450—1600 

Wax,  Japanese 

0-99 

54 

,        white       .... 

0-96—0-97 

63 

,        yellow      .... 

0-96-0-97 

62 

Wood,  beech     -         -         -        •    ' 

0-85 

box         -         ... 

1-33 

elm         .... 

0-80 

oak        - 

0-7—0-8 

poplar    --.. 

0-40 

yellow  pine  - 

0-66 

Zinc  

7'15 

412^20 

930—950 

LIQUIDS. 


Acid,  hydrochloric    - 

1-24 

,,       nitric       .... 

1-42 

,,       sulphuric 

1-84 

Alcohol,  ethyl    - 

0-7911 

-130 

78-3 

,,         methyl,  wood 

o-so 

66 

Amyl  acetate     - 

0-90 

140 

Aniline,  oil 

1-02 

185 

Benzol,       

0-881 

5 

80-3 

Carbon  disulphide     - 

1-265 

-113 

46 

Chloroform         -         - 

1-53 

-70 

61-2 

Ether,  sulphuric        -         -         - 

0-717 

-118 

34-9 

Glycerine  - 

1-24—1-26 

-20 

290 

Mercury 

13-596 

-38-8 

357 

Oil,  linseed        ... 

0-93 

,,     olive   - 

0-91 

Petroleum,  crude       -        -        - 

1-75—1-84 

,,            refined     -        -        . 

0-84 

,,            rhigolene 

0-65—0-66 

40—70 

,,            gasolene  - 

0-66—0-69 

70-90 

,,            benzene  - 

0-69  -0-70 

90—110 

Phenol,  carbolic  acid 

1-08 

40 

180 

Turpentine,  oil  - 

0-87 

GASES. 


Air     

0-001293 

-200 

Carbonic  acid    -      4  -   - 

1865 

-57? 

-  78  to  -  80 

Hydrogen  -         -         - 
Nitrogen 

0901 
1251 

-250 
-203  to  -214 

-256 
-194 

Oxygen      

1429 

-  181  to  -  184 

Water  vapor      .... 

0804 

0 

100 

292     EVOLUTION   OF   WEIGHTS   AND   MEASURES 


THERMOMETER   SCALES. 
CENTIGRADE  AND  FAHRENHEIT  EQUIVALENTS. 

For  Absolute  Temperatures  add  273°  to  Centigrade  Scale. 


Centigrade. 

Fahrenheit. 

Remarks. 

Centigrade. 

Fahrenheit. 

Remarks. 

-273 

-549-4 

'  '  Absolute  zero.  " 

-6-1 

21 

' 

-250 

-418 

Hydrogen  boils. 

-6 

21-2 

-200 
-190 

-328 
-310 

Temp,  liquid  air. 
Nitrogen  boils. 

-5-6 
-5 

22 
23 

-180 

-292 

Oxygen  boils. 

-4-4 

24 

-170 

-274 

-4 

24-8 

-160 

-256 

-3'9 

25 

-150 

-238 

-  3-3 

26 

-140 

-220 

-3 

26-6 

-130 

-202 

Alcohol  freezes. 

-2-8 

27 

-120 

-184 

-2-2 

28 

-110 

-166 

-2 

28-4 

-100 

-148 

-1-7 

29 

-80 

-112 

Carbonic  acid  gas 

-1-1 

30 

-60 

-76 

boils. 

-1 

30-2 

-40 

-40 

Mercury  melts. 

-0-6 

31 

-30 

-22 

Ammonia  boils. 

0 

32 

Water  freezes. 

-25 

-13 

0-6 

33 

-20 

-4 

1 

33-8 

-19 

-2-2 

1-1 

34 

-18 

-0-4 

1-7 

35 

-17-8 

0 

2 

35-6 

-17-2 

1 

2-2 

36 

-17 

1-4 

2-8 

37 

-16-7 

2 

3 

37-4 

-16-1 

3 

3-3 

38 

-16 

3-2 

3-9 

39 

-15-6 

4 

4 

39-2 

Maximum  density 

-15 

5 

4-4 

40 

of  water. 

-14-4 

6 

5 

41 

-14 

6-8 

5-6 

42 

-13'9 

7 

6 

42-8 

-  13-3 

8 

6-1 

43 

-13 

8-6 

6-7 

44 

-12-8 

9 

7 

44-6 

-12-2 

10 

7-2 

45 

-12 

10-4 

7-8 

46 

-11-7 

11 

8 

46-4 

-11-1 

12 

8-4 

47 

-11 

12-2 

8-9 

48 

-10-6 

13 

9 

48-2 

-10 

14 

9-5 

49 

-9-4 

15 

10 

50 

-  9 

15-8 

10-6 

51 

-8-9 

16 

11 

51-8 

-8-3 

17 

11-2 

52 

-8 

17-6 

11-7 

53 

-7'8 

18 

12 

53-6 

-7-2 

19 

12-3 

54 

-7 

19-4 

12-8 

55 

-6-7 

20 

13 

55-4 

THERMOMETER   SCALES 


293 


THERMOMETER  SCALES. 
CENTIGRADE  AND  FAHRENHEIT  EQUIVALENTS. 

For  Absolute  Temperatures  add  273°  to  Centigrade  Scale. 


Centigrade. 

Fahrenheit. 

Remarks. 

Centigrade. 

Fahrenheit. 

Remarks. 

13-3 

56 

33 

91-4 

13-9 

57 

33-3 

92 

14 

57-2 

33-9 

93 

14-4 

58 

34 

93-2 

15 

59 

34-4 

94 

Ether  boils. 

15-6 

60 

35 

95 

16 

60-8 

35-6 

96 

16-1 

61 

36 

96-8 

16-7 

62 

36-1 

97 

17 

62-6 

36-7 

98 

17-2 

63 

37 

98-6 

Human  blood  tem- 

17-8 

64 

37-2 

99 

perature. 

18 

64-4 

37-8 

100 

18-3 

65 

38 

100-6 

18-9 

66 

38-3 

101 

19 

66-2 

38-9 

102 

19-4 

67 

39 

102-4 

20 

68 

Proper  room  tem- 

39-4 

103 

20-6 

69 

perature. 

40 

104 

21 

69-8 

43-3 

110 

21-1 

70 

45 

113 

21-7 

71 

48-9 

120 

;, 

22 

71-6 

50 

122 

22-2 

72 

54-4 

130 

22-8 

73 

55 

131 

23 

73-4 

60 

140 

Chloroform  boils,  62*. 

23-3 

74 

65 

149 

Potassium  melts,  62°. 

23-9 

75 

65-6 

150 

Methyl  alcohol  bis.  ,66*. 

24 

75-2 

70 

158 

Woods  alloy  melts,  65°. 

24-4 

76 

71-1 

160 

25 

77 

75 

167 

25-6 

78 

76-7 

170 

26 

78-8 

80 

176 

Ethyl  alcohol  boils,  79°. 

26-1 

79 

82-2 

180 

26-7 

80 

85 

185 

27 

80-6 

87-8 

190 

27-2 

81 

90 

194 

27-8 

82 

93-3 

200 

28 

82-4 

95 

203 

Sodium  melts,  96°. 

28-3 

83 

98-9 

210 

28-9 

84 

99 

210-2 

29 

84-2 

99-4 

211 

29-4 

85 

100 

212 

Water  boils,  under 

30 

86 

125 

257 

76  cm.  pressure. 

30-6 

87 

150 

302 

31 

87-8 

Critical   tempera- 

175 

347 

31-1 

88 

ture  of  carbonic 

200 

392 

Solder  melts,  183°. 

31-7 

89 

acid. 

250 

482 

Tin  melts,  227°. 

32 

89-6 

300 

725 

Lead  melts,  335°. 

32-2 

90 

350 

662 

Mercury  boils, 

32-8 

91 

400 

752 

357°  '3. 

294     EVOLUTION   OF   WEIGHTS   AND   MEASURES 


MISCELLANEOUS   CONSTANTS  AND  EQUIVALENTS. 

7r  =  3-1416.  7r2  =  9-8696.  l/7r  =  0-31831.  47r=  12-566. 

l/47r  =  0-07958.  logir  =  -49715.  log  7r2=-  99430.  log  l/ir=f '50285. 

log  4T=  1-09921.          logl/47r=2-90079. 

Base  of  the  natural  system  of  logarithms,  e  =  2'7183,     loge  =  -43429  (Briggs). 

Modulus      ,,  „  „         M  =  I/log e  =  2-3026,  log  M=  -36222  (Briggs). 

Radian  =  angle  where  the  arc  equals  the  radius  =  57° '2958  =  3437' '75  =  206265". 
log  radian  (in  degrees)  =  1  '75812,         (in  minutes)  =  3 '53628, 
(in  seconds)  =  5 -31443. 

Steradian  =  the  solid  angle  at  the  center  of  a  sphere  of  unit  radius  which  is  sub- 
tended by  the  unit  area.     Total  angle  at  a  point  equals  4?r  steradians. 

Earth's  radius  in  kilometers — 

equatorial  =  6378 -2,  polar  =  6356 '5,  mean  =  6367 '4, 

log  equatorial  =  3 -80469,         log  polar  =  3 '80321,         log  mean  =  3 '80396. 

Mean  solar  year  =  365 -2422  days  =  8765 '8 13  hours  =  525948 '8  min.  =31556928  sec. 

Stellar  day  is  3  min.  55 '9  sec.  shorter  than  the  mean  solar  day,  =0  "99727  day. 

Velocity  of  sound  in  dry  air  at  0°C.  is  331  meters  per  second. 

Coefficient  of  expansion  of  gases  =  1/273=  '003665. 

Acceleration  of  gravity  at  poles  =  983  '2 ;  at  equator  =  978  '0 ;  at  45°  =  980  '6 ;  at  New 
York  =  980-2  ;  at  Greenwich  =  981 '2  ;  at  0°  latitude  =  978 (l+0'0052sm20). 

1  gram  of  water  1°C.  =  minor  calorie  =  4  -2  x  107  ergs  —  4  "2  joules. 

Latent  heat  of  water  =  80;  of  steam  =  539. 

Specific  heat  of  air  at  constant  pressure  =  0'237.     Ratio  of  specific  heats  =  1  "40. 

Capillary  constant  of  water  =  7 '7,  of  alcohol  =  2 '3,  of  mercury  =  50  rng./mm. 

Velocity  of  light  in  vacuo  =  3  x  1010  cm. /sec. 

Wave  length  of  sodium  light  =  0*0005893  mm. 

Length  of  the  meter  in  wave  lengths  of  red  cadmium  light  =1553163 '5. 

1  ampere  of  current  deposits  1-118  mgr.  of  silver  per  second  =  0'1740c.c.  (H.  audO.). 

A  plate  of  quartz  1  mm.  thick  at  18°  C.  rotates  the  plane  of  polarization  21° '71. 

Ohm  =  resistance  of  a  column  of  mercury  1  sq.  mm.  cross-section,  106 "3  cm.  long. 

E.M.F.  of  Latimer  Clark  cell  at  18°  is  1-434,  of  cadmium  (Weston)  cell  at  4°  is 
1-0190. 

The  solar  constant  =  3  gram-calories  per  sq.  cm.  per  minute. 

The  mass  of  the  hydrogen  atom  is  =  10-24  gram  ;  of  the  electron  is  =  10~27  gram. 

Value  of  e/m  =  4'5  x  1017  electrostatic  =  1  '5  x  107  electromagnetic. 

Velocity  of  the  electrons — beta  particles  =  2'7  x  1010,  alpha  particles  =  3  x  109. 

Probable  speed  of  a  molecule  of  oxygen  at  0°  C.  =376 '6  m./sec.,  of  hydrogen  =  1500"9. 

Mean  free  path  of  a  molecule  of  air  at  a  pressure  of  76  cm.  and  at  0°  C.  =9  "6  x  10~6. 

Number  of  molecules  of  air  in  a  c.c.  at  0°  C.  and  76  cm.  =6  x  1019. 

One  atmosphere  pressure  =  76  cm.  of  mercury  =  1-0132  megadynes  per  sq.  cm. 

A  knot  is  a  speed  of  one  nautical  mile  per  hour  =1 '1515  statute  miles  or  1853'25 
meters  per  hour. 

A  miner's  inch  of  water  is  from  1*20  to  1*76  cu.  ft.  per  min.  =0*708  liter  per  sec. 

Ratio  of  the  probable  error  to  the  mean  error  is  0*6745  (2/3). 

Light  year  is  the  distance  travelled  by  light  in  one  year  =  9  "467  x  1012  kilometers 
=  5 -8825  xlO12  miles. 


INDEX. 


PAGE 

Abbot.  Gen.  Henry  L.          -         -     211 

Abraham 4,  19 

Absolute  measurements  -  -  204 
Absolute  system  -  -  -  -  200 
Academy  of  Sciences,  Paris,  47,  48,  65 
Academy  of  Sciences,  Paris,  Sup- 
pression of  -  -  -  -  52 
Academy  of  Sciences,  National, 

U.S.       -        -               127,  129,  210 
Academy  of  Sciences,  St.  Peters- 
burg        71 

Acts  of  Congress 

119,  121,  127,  128,  129,  131,  132,  210 

Actus 26 

Adams,  John  Quincy 

109,  115,  116,  117,  118 
Aeginetan  talent  and  mina  -  27,  28 
Airy,  Sir  G.  B.  -  -  -  100,  247 

Ale  gallon 35 

Alexandrian  talent  -  -  25,  32,  33 
Alloys,  Nickel  steel  -  -  -  221 
Amenoetnopht  -  -  -.  -  22 
American  Geographical  and  Statis- 
tical Society  -  -  -  -  125 
American  Metrological  Society  -  129 
Ampere  -  206,  207,  208,  209,  211 

Amphora 28 

Angle,  Measurement  of  -  -  202 
Anglo-Saxon  measures  of  length  -  36 
Angular  acceleration  -  -  -  202 
Angular  velocity  -  202 

Anti-Metric  argument  of  American 
Society  Mechanical  Engineers 

145-162 
Apothecaries'  pound  32 

Ar 142 

Arabs,  Measures  of   -    -    29,  38 

Arago 100 

Arbitrary  units    ....         5 

Arbuthnot 10 

Arc  of  Meridian,  Measurement  of  55 
Archinne 94 


Are       - 

Argentine  confederation 

Ark,  Dimensions  of 

Aroura 

Arpent 


PAGE 

-  54 

-  76 

-  11 
20,23 

-  45 


Articles  of  confederation,  Weights 

and  measures  in     -         -         -  109 

As,  Roman  unit  of  weight    -         -  26 
Assize  of  bread  and  ale           32,  35,  242 

Association  geodesique          -         -  71 
Assyrian     documents,     Measures 

in  -  16 

Astronomy,  Babylonian        -         -  12 

Ater     -         -         -         -         -        -  23 

Athena,  Temple  of                 •         -  25 

Athenian  talent  27 

Attic  foot     -         -         -.-         -  25 

Aulne,  Derivation  of    -         .        -  26 

Aune  des  marchands  38 

Aune  of  Paris       -         -        -  38 

Aune,  Swiss  97 

Australia  and  the  metric  system  -  102 

Austria  adopts  metric  system       -  90 
Austria -Hungary      signs     metric 

treaty 75 

Autun,  Talleyrand,  Bishop  of       -  46 
Avoirdupois  pound 

33,  34,  35,  122,  123,  248 

Babylonia,  Measures  of  8,  9,  11,  12,  13, 
14,  15,  16,  17,  18,  19,  22 
Bache,  Professor  A.  D.  122,  123,  124 
Baden  adopts  decimal  measures  -  82 
Baily,  F.  -  -  -  -  231,  243 
Balance  -  24,  236,  237,  238,  239 


Baldwin  locomotive  works 
Bancroft,  George  - 
Barcelona 
Barker,  Geo.  F.    - 
Barley  corn  as  a  unit 
Barnard,  Prof.  F.  A.  P 
Barus,  Carl  - 


-  188 

-  125 
49,  56 

-  211 
-8,  29 

-  129 

-  211 


296 


INDEX 


PAGE 

Base  measurement  55 

Bassot -  41 

Bath 20 

Beal 6 

Belgic  foot 31 

Belgium  adopts  metric  system      -  91 

Belhaven  and  Stenton,  Lord         -  101 


Benoit,  J.  Rene 
Berthollet     -         - 
Bessel 

Bigourdan,  M. 
Binary  subdivision 
Bird  standard       - 
Bismer-pund 
Black  cubit 
Elaine,  James  G.  - 


69,  219,  251 

-  54,  99 
40,  223 

-  41 

-  -  179 

-  -  244 

96 
29 

-  -  159 


Board  of  Trade  British  specifica- 

tions .....  215 
Board  of  Trade  electrical  stan- 

dards    .....     242 

Body  measures  6 

Boeckh         -        -        -        -  11,  29,  30 

Boisseau        .....       66 

Borda  -         -         -    47,  48,  54,  250,  251 
Brandis,  J.   .....       11 

Brazil  and  metric  treaty       -         -       75 
Briggs,  Ernest  E.  -         -     187 

Brighton  railway,  England  -         -     168 
Brisson          .....       54 

British  Association  committee  on 

units  ....  205,  207 
British  Association  unit  of  resist- 

ance .....  207 
British  engineers  in  Egypt  -  -  92 
British  imperial  gallon  -  -  36 
British  imperial  standards 

245,  246,  247,  248,  249 
British  imperial  standard  yard  -  246 
British  pharmacopoeia  -  192,  197 
British  standards  of  length  and 

weight  -  245,  246,  247,  248,  249 
British  Weights  and  Measures 

Association    -  163 

Brix      .--  -      69 

Bronze  standard  No.  11  -  -  247 
Brumaire  .....  53 
Brumer  comparator  -  -  -  234 
Bunge  balance  -  238 

Bureau  International  des  Poids  et 

Mesures  established  -  -  76 
Bureau  of  Standards,  U.S.  -  131,  132 

Cadmium  spectrum,  Lines  of  -  261 
Calendar,  French  reforms  in  52,  53 
Caliph-Al-Mamum  29 

Calipers  for  standards  of  length 

224,  229 

Canaan,  Civilization  of  -  -  19 
Capacity,  Electrical  -  -  203,  209 


Capacity,  Measures  of 

5,  27,  28,  35,  144,  240 

Carat 3,  25 

Cassini  -  -  -  -  44,  49,  54 
Cattle  standard  ...  3 

Centesima 43 

Centigram    -         -         -      146,  147,  148 

Centiliter 144 

Centime 45 

Centimeter 139 

Centner 86 

Centuria 43 

C.G.S.  or  centimeter-gram-second- 
system  -        -       102,  199,  205,  206 
C.G.S.  electro-magnetic  units     -       207 
Chambers  of  Agriculture  favour 

metric  system  -  -  -  102 
Chaney,  H.  J.  -  -  30,  37,  247 
Chappuis,  M.  -  -  -  261 

Charlemagne  37 

Charlemagne,  "Pile  de"  -  -  39 
Chase,  Salmon  P.  ...  126 
Chicago  congress  ....  208 
Chisholm,  H.  W.  -  -  25,  32,  33,  244 
Clark  cell  -  -  -  -  -  207 
Clark,  Capt.  A.  R.  -  -.  -  69 
Clarke's  spheroid-  62 

Coast  and  Geodetic  Survey  stand- 
ards -  -  -  114,  121,  122 
Colles,  Geo.  W.  -  -  -  -  133 
Collet,  M.  A.  -  -  .  -  '"  -  258 
Cologne,  Mark  of  -  -  32,  40 
Colonial  Governors,  British,  favour 

metric  system  -  -  -  159 
Commemorative  medal  for  metric 

system  -  -  -  -  63,  64 
Commercial  pound  (libra  mercatoria)  33 
Committee  on  coinage,  weights 

and  measures  reports       73,  75,  87, 
90,  91,  120,  121,  128,  130,  133 
Committee  of  weights  and  measures 
and  of  moneys  of  Paris  Ex- 
position of  1867  -         -       85 
Comparison  of  standards  of  length     229 
Comparator  of  Borda    -         -         -     230 
Comparator  of  Lenoir  -         -         -     230 
Compensated  bars         -         -         -     251 
Conder,  C.  R.        -         -         -         -       22 
Condorcet     -         -         -         -         47,  48 
Conference    of    British     Colonial 

Premiers        -         -         -         -     159 

Congius 28 

Congress,  U.S.,  considers  weights 

and  measures          -  113,  127 

Congress,  Acts  of 

119,  127,  128,  131,  132 
Conservatoire  des  Arts  et  Metiers 

69,  250,  251,  252 
Conservatory,  Meter  of  73 


INDEX 


297 


Continental  Congress,  legislation 

on  weights  and  measures,  -  109 
Corinth,  Units  of  weight  in  -  -  27 

Corn  bushel 35 

Corn  gallon 35 

Corps  Legislatif  receives  standard 

meter  and  kilogram  -  -  63 
Cotton  values  quoted  decimally  -  167 
Coulomb  54 

Coulomb,  unit  of  quantity  203,  206,  207 
Cross-wires  ....  231,  234 
Crypt  chapel  ....  30 
Crystal  standards  -  -  -  236 
Cubit  -  6,  13,  14,  15,  20,  22,  26 

Cunin-Gridaine  83 

Currency,  Decimal  -  -  85,  110 
Curvature,  Unit  of  202 

Dagobert 37 

Daniell  cell 205 

Deben  or  uten  24 

De  Bonnay,  Marquis  46 

Decagrams  ....  146,  148 
Decaliter  ....  144,  145 
Decameter  -  138,  139 

Decigrams    -         -         -  146,  148 

Deciliter 144 

Decima 43 

Decimal  Association  -  -  -  101 
Decimal  clocks  -  -  -  -  168 
Decimal  hour  ....  168 
Decimal  multiplication  -  -  167 
Decimal  system  of  coinage  -  85,110 
Decimal  system  of  Jefferson  -  111 
Decimal  system  of  money  pro- 
posed in  France  45 

Decimes 45 

Decimeter     -  -      138,  139 

Decistere      -  -     144 

Decuria 43 

Didrachms 25 

Delambre  -  -  -  -  54,  60 
Delambre  and  Mechain,  Base  du 

Systeme  Mttrique  -        -  41 

De  Luc 99 

Denier '      -       38 

Denmark  signs  metric  treaty  -  76 
De  Pury,  Charles  A.  -  168 

De  Sarzec,  E.  -       14 

De  Schubert,  Gen.  T.  F.  -  -  69 
Dessert-spoonful  -  -  -  198 

Digit 6 

Directive  force  -  -  -  -  202 
Dividing  engine  ....  225 
Domesday  book  -  -  -  31 

Double  weighing  -  237 

Drachmas 27 

Draughting  room,  Metric  system 

in 181 


Drusus,  Foot  of  - 
Dunkirk  -  - 
Du  Vernois,  Prieur 

Earth  inductor 
Edgar,  Laws  of     - 
Edward  I.,  Laws  of 
Edward  II..  Laws  of    - 
Edward  III.,  Laws  of  - 


PAGE 

-  26 
49,  56 

-  44 

-  204 

-  30 

-  34 
36,  242 

-  243 

-  92 


Egypt,  metric  measures 
Egyptian  measures,  Ancient 

11,  20,  22,  23,  24 

Ehalkus        -         -  -         -       27 

Electrical  congress,  Chicago  208,  216 
Electrical  congress,  Paris  -  -  215 
Electrical  congress  (St.  Louis)  216,  241 
Electrical  measure,  U.S.  units  of  131 
Electromotive  force  -  -  -  204 
Elephantis,  Cubit  of  -  -  -  22 
Elizabeth,  Standards  of  34,  36,  243 

Ell 26,  36,  89 

Elle 83 

End  standard  (metre  a  bouts)  -  74 
End  standards  (etalon  a  bouts)  -  223 
Energy,  Unit  of  -  -  -  -  202 
Engineering,  Metric  system  in  -  172 
England,  Progress  of  metric 

system  in       -         -         -         -       98 
English  Bible,  Weights  and  meas- 
ures in 20 

English    parliamentary    accounts 

and  papers  91 

English  yard 

3,  31,  36,  243,  244,  245,  246 
Ephah  -  20 

Eratosthenes  29 

Erg 202,  206 

Euboic  talent  27 

Everest,  Col.  George  69 

Exchequer,  Standards  of  -  34,  109 
Exodus,  Weights  and  measures  at 

time  of  -  -         -       20 

Export     business     and     uniform 

measures        ....     133 
Ezekiel          ....         20,  23 

Fabbroni 256 

Farad  -  -  -  203,  206 
Farmers'  Associations  favour 

metric  system  -  -  102 

Fathom  6 
Federal  constitution,  Weights  and 

measures  in  -  -  -  -  109 

Finland,  metric  system  adopted  -  95 

Fizeau 261 

Fleetwood,  Bishop  ...  30 

Floreal 53 

Foerster,  W.  -  -  -  87 

Foot  6,  25,  26,  31,  37,  38,  44,  89,  112 


298 


INDEX 


PAGE 

Force,  Units  of     -  200,  202 

Forney,  M.  N.  -  -  -  -  185 
Foster,  Secretary  of  State  -  -  159 
France,  Measures  of  -  -  37,  43 
French  Academy  99 

French  foot 38 

French  standards  of  length  -  37,  249 
French  standards  presented  to 

various  nations  83 

French  standards  of  weight         38,  250 

Fructidor 53 

Fundamental  units  -  -  S,  200 
Fuss 83 

Galileo 15 

Gallatin,  Albert,  Minister  -  119,  121 
Oambey,  Comparator  of  -  69,  232 

Gan 15 

Gar 15 

Garden 15 

Gas  thermometer  -  -  -  228 
Gauges  -  -  -  176,  177,  178 
Gauss,  Carl  Friedrich  -  -  200,  201 
Gauss  (unit)  ....  215 
Genesis  11-19 

Geodetic  or  trigonometrical  survey 

42,  55 

"Geometrical"  inch  -  -  -  164 
Geometric  foot  -  -  -  -  43 
German  Magnetic  Union  -  -  200 
Germany,  Metric  system  in 

86,  87,  88,  89,  90 
Ghizeh,  Pyramid  of      -         -     9,  22,  24 

Gin 15 

Gird 30 

Godin  and  Bouguer  44 

Goldsmith's  Hall,  Standard  of      -     248 

Gore,  J.  H. 43 

Gouon  and  Penin  64 

Gradus 26 

Graham,  George  36 

Gram 54,  146 

Gratings,  Diffraction  -  -  -  226 
Gravimetric  method  -  -  -  193 
Great  circle  42,  48 

Great  mina 16 

Great  pyramid  -  -  7,  9,  22,  24 
Greaves,  John  29,  30 

Greece,  Measures  of  ancient  -  25 
Greece,  Metric  system  in  -  -  92 
Greek  cubit  -  -  -  -  22,  25 
Greek  foot  -----  25 
Gregorian  calendar  resumed  in 

France 53 

Griffiths,  F.  L.      -         -         -         -       23 

Gros 39,  66 

Gudea  scale-  13,  14 
Gunter,  Edmund  9S 

Gur 16 


Guillaume,  Ch.  Ed. 

vii.,  35,  39,  221,  223,  228 
Guizot 83 

Halsey    and    Dale,     The    Metric 

Fallacy 134 

Hamy,  M. 261 

Hand-breadth  -  -  •  -  6,  13 
Harpham,  F.  E.  -  -  -  -  41 

Harris 34 

Harrison,  President  Benjamin  -  131 
Hassler  -  -  114,  121,  122,  123 
Hastings,  Charles  S.  -  -  -  211 
Haute-Guyenne  -  -  -  -  45 
Haiiy  -  -  -  -  -  54,  62 
Hebrew  weights  and  measures 

19,  20,  21 

Hectar(e)  -  -  -  -  51,  142 
Hectogram  -  -  -  -  51,  148 
Hectoliter  -  ...  51,  145 
Hectometer  -  -  -  -  51,  139 
Hekatompedos  •  -  -  25 

Hekt 23 

Henry  (unit)  -  -  -  -  210 
Henry  I.,  Yard  of  -  -  -  3,  31 
Henry  III. ,  Statutes  of  -  32,  33 
Henry  IV.  ...  33 

Henry  VII.  -  -  -  -  34,  35 
Henry  VIII.,  Statutes  of  -  34 

Henry,  Prof.  Joseph  -  -  -  129 
Henu  -  -  -  --.-•-  23 
Herschel,  Sir  John  -  -  7,  164 
Hilgard,  J.E.  ....  129 
Hin  -  21 

Hindus,  Weights  and  measures  of  18 
Hiuen-Tsiang  -  -  -  -  6 
Holland,  Metric  system  in  -  82,  93,  94 
Holton,  Michigan,  Base  at  -  -  141 
Homer  -  -  -  -  -  21 
Hommel  -  -  -  11,  12,  13 

House    of    Commons    Committee 

report 100 

House  of  Deputies,  France,  bill  -  67 
Hultsch  ....  25 

Hundredweight  ...  -  156 
Hungary,  Metric  system  in  -  -  91 
Hunt,  Wm.  H.  -  -  -  -  195 

Huygens 43 

Hydrogen  scale  ....  228 
Hydrogen  thermometer  -  -  228 

Ibanez,  General  77 

Iced  bar  base  apparatus         -         -     141 

Ideler,  L. 12 

Imperial  bushel  -  -  -  35,  249 
Imperial  standards 

245,  246,  247,  248,  249 

Inch 26,  36 

India,  Ancient  measures  of  -         -         6 


INDEX 


299 


PAGE 

Inductance,  Unit  of      -  208 

Ingham,  S.  D.  -  -  -  120,  121 
Institution  of  Electrical  Engineers  186 
Instruments  of  precision,  Use  of 

metric  system  in    -         -         -     181 
Intensity  of  magnetism,  Measure- 
ment of 200 

International  American  Conference 

of  1890  -  103,  159 

International  ampere  -  -  -  209 
International  Bureau  of  Weights 

and  Measures         -  75,  76,  77,  129, 
221,  226,  260 
International  Commission 

61,  72,  97,  216 

International  Congress  of  Elec- 
tricians (Chicago)  -         -         -     208 
International    Congress   of    Elec- 
tricians (Paris)       -         -     207,  208 
International   Congress    of    Elec- 
tricians (St.  Louis)         -         -     216 
International       Convention       of 

Weights  and  Measures  -  75 
International  Coulomb  -  -  209 
International  electrical  units 

131,  199,  209 

International  farad  -  -  -  209 
International  Geodetic  Association  71 
International  kilogram,  Definition 

of 78 

International  metric  commission 

72,  73,  74,  75,  76,  77,  78 
International    metric     prototype 

standards     -  76,  77,  252,  254,  255, 
256,  257,  258,  259 

International  ohm  -  -  207-209 
International  Postal  Convention  127 
International  Postal  Union  -  -  151 
International  prototype  meter 

130,  136,  221,  252,  255 
International  standard  kilogram 

78,  258,  259 

International  Statistical  Congress  1 26 
International  volt  -  -  209 

Invariability  of  standards  -  219,  260 
Israelites,  measures  -  -  19,  20,  21 
Italy,  Metric  system  in  -  -  93 

Jacobi 205 

Japanese  weights  and  measures  -  93 
Jefferson,  Thomas 

110,  111,  112,  113,  114,  115 

Jeremiah 23 

Jews,  Weights  and  measures  of    -       19 


Johns,  Rev.  C.  H   U. 

Josephus 

Jomard 

Joule    - 

Jugerum 


-  16,  17,  18 

-  10 
10,  30 

206,  208,  209 

-  26 


PAGE 

Ka 16 

Kab 16,  21 

Karsten 40 

Kasbu 15 

Kat  or  Kiti 24 

Kater,  Captain  Henry 

99,  100,  119,  120,  122,  222,  245 
Keith,  Rev.  George  Skene    -         -       99 

Kelly 31,37 

Kelvin 101 

Kennedy,  A.  R.  S.        -         -         -       20 

Khar 23 

Khet 23 

Kilogauss 215 

Kilogram     50,  62,  63,  73,  74-146, 

147,  256,  257,  258,  259 
Kilogram  of  the  Archives 

73,  74,  75,  147,  256,  257,  258 
Kilometer  50,  138 

Kilowatt 206 

King  Edgar  -  -        -         -       30 

Kirwan 98 

Kiti  or  Kat 24 

Koenigsberg  standard  -  -  -  223 
Kohlrausch,  Rudolf  -  -  201,  205 

Kor 21 

Korn-Tonde 96 

Kupffer 234 

Lacaille 49 

La  Condamine  ....  44 
Lagrange  -  -  -  -  47,  48,  54 

Lalande 229 

Laplace  -  -47,  48,  54,  65,  98,  99 
Larsam  or  Larsa  -  -  -  -  13 

Lathes 182 

Latin  prefixes  -  -  -  -  137 
Latin  Union  85 

Latitude,  Determination  of 

56,  57,  58,  59 

Lavoisier  -  -  -  -  62,  98,  99 
Leading  screw  of  lathes  -  -  187 
Lefevre-Gineau  -  -  -  62,  256 
Lehmann  -  -  -  -  15,  18 
Lenoir-  -  -  114,230,251,256 
Lepsius  -...  i3f  22 
Leroux,  Alfred  -  -  -  -  71 
Lever  comparator  -  -  -  230 

Le  Verrier 69 

Libbrae  metrica    -         -         -         -       82 

Libra 28 

Libra  mercatoria  -         -         -       33 

Library  catalogue  cards        -         -     140 

Lieue 97 

Lignes  -  44,  45 

Line  and  reel  -  -  -  -  23 
Line  standards  (etalon  a  traits)  -  223 
Linnard,  J.  H.  -  -  -  134 
Liter 54,  145 


300 


INDEX 


PAGE 

Liverpool  Cotton  Association        -     167 

Livre 39,  45,  97 

Livre  de  Troyes  83 

Livre  Esterlin  32,  38 

Livre  poid  de  marc  39 

London  Exposition  of  1851  -         83,  84 

Longitude 59 

Long  ton 168 

Louis  XVI. 45 

Lumber,  Measurement  of     -         -     178 

Maass  concordats  -         -         83,  97 

Machine  shop,  Metric  system  in  -  182 
Madison,  President  James  -  -  115 
Magna  Charta,  Weights  and 

measures  in    -         -         -  32 

Magnetic  field,  Unit  of  -  -  203 
Magnetic  pole,  Unit  of  -  -  202 
Maine  approves  metric  system  -  122 
Mairan,  Toise  of  -  -  -  -  61 

Marc 39 

Marc  de  Troyes  33 

Marine  Hospital  Service  -  192-195 
Mark  of  Cologne  32,  40 

Mass,  Measures  of  -  -  -  146 
Master  Car  Builders'  Association 

173,  185 

Mauss,  C. 250 

Maxwell,  (unit)  -  -  -  203,  215 
Maxwell,  J.  Clark  -  -  -  260 
Measures  of  capacity  -  -  144,  240 
Mechain  -  -  -  41,  54,  60,  61 
Mechanical  engineering  and  manu- 
facturing, Metric  system  in  -  172 
Mechanical  engineers,  American 

Society  of       -  -       145-162 

Medical  department  of  the  army 

192,  195,  196 
Medical  department  of  the  navy 

192,  195 

Medical  papyri  24 

Medicine  and  pharmacy,  Metric 

system  in  191 

Medimnus     -         -         -         -         -      23 

Megameter 138 

Memphis,  Necropolis  at  -       22 

Memphis-Faium  road  23 

Mendenhall,  J.  C.  -  -  -  164 
Mesures  usuelles  -  -  65,  66,  67 

Meter         -         -  49-54,  62-63,  139 

Meter  of  the   Archives  62,  71,  73,  75, 
221,  225,  249,  251 

Meter  of  the  conservatory    -       63,  251 
Meter  of  the  observatory      -         -     251 
Method  of  interference  for  measur- 
ing differences  of  length         -     225 
Metre  a  bouts  74 

Metre  &  traits  -  -  -  72,  73,  74 
Metric  measures  of  capacity  144,  240 


Metric  measures  of  length  - 

Metric  measures  of    mass  - 

Metric  measures  of  surface  - 

Metric  measures  of  volume  - 
Metric  prescriptions 


PAGE 

138 
146 
142 
143 
192 


Metric  standard    of    U.S.    Coast 

Survey 114 

Metric  standard  of  United  States  130 
Metric  system  -  -  39,  41,  61,  63 
Metric  system  in  U.S.  Congress 

133,  134 

Metric  thread  ....  183 
Metric  ton  -----  147 
Metric  wire  gauges  -  -  -  178 
Metrological  Society,  American  -  129 
Mexico,  Metric  system  in  -  -  103 
Michelson,  Prof.  A. 

211,  260,  261,  262,  263,  264,  265 

Micro-farad 206 

Micrometer-microscope 

230,  231,  233,  234 

Micrometer  screws  -  -  -  229 
Micron  -  -  -  -  140 

Milan,  Metric  system  introduced 

in 82 

Mile  -  ....  26,31 
Milia  pasuum  -  -  •  26,  31 
Miller,  W.  H.  -  -  -  35,  248 
Miller,  Sir  John  Riggs  -  99,  163 
Milligram  -  ...  146,  148 
Milligram,  weights  -  -  -  148 

Milliliter 144 

Millimeter  -  ...  138,  140 
Millimicron  .  .  .  138,  140 

Mina  -         - 16,  21,  25,  27,  28,  32 

Mina,  Babylonian  16 

Mina,  heavy          -         -         -         -       16 

Mina,  light 16 

Mina,  Phoenician  16 

Mint,  U.S.,  standard  troy  pound      119 

M'Leod 99 

Modius 28 

Moment  of  rotation,  Unit  of  -  202 
Momentum,  Unit  of  202 

Monge 48,  54,  99 

Moore,  Dr. 123 

Morin,  General  A.  -  -  41,  69 
Morris,  Robert  -  -  -  -  110 
Mouton,  Gabriel  -  -  -  -  43 

Miinzpfund 86 

Myriameter 138 

Myriagram  -  146,  147 

Napoleon  I.  -  -  -  65,  77,  82,  92 
Napoleon  III.  -  -  -  -  71 
National  Academy  of  France  -  49 
National  Academy  of  Sciences, 

U.S.       -         -         -      127,129,211 
National  Assembly  (French)         -       46 


INDEX 


.301 


PAGE 

National  Bureau  of  Standards  132 

National  Institute  of  Sciences  and 

Arts  (French)  -  53,  63 

National  Physical  Laboratory 

(England)  -  -  -  152,  241 
National  prototype  meter  of  the 

United  States  -  -  -  130 
Natural  standards  ...  5 
Natural  units  ....  5 
Neutral  plane  ....  222 
New  Hampshire  approves  metric 

system 125 

Newton's  rings  ....  261 
New  Zealand  adopts  metric  system  102 
Nickel  five  cent,  piece-  -  -  128 
Noak,  Ark  of  -  -  -  -  11 
Normal-Aichungs-Kommission  87,  90 
North  German  Confederation  -  87 
Norway  -  -  -  -  95,  96 


Oboles  - 
Ohm      - 
Ohm's  law    - 
Oke       - 
Oldberg,  Oscar 


38,  39 

-  206 
204,  206 

-  92 
195 


Old     Testament,     Weights     and 

measures  of  -         -         -  19,  20,  21 
Olympian  foot  25 

Oner 21 

Opticians'  use  of  metric  system  -  181 
Orguia,  or  fathom  25 

Origin  of  weights  and  measures  -  1 
Ounce  -  -  -  -  25,  26,  32,  33 

Pace 2,  6 

Palestine       Exploration       Fund, 

Quarterly  statement,  1902     -       22 

Palm 6 

Palm,  Babylonian  -  -  -  14 
Palmipes  or  foot  -  26 

Parasang 15 

Paris  Academy  of  Sciences  46,  47,  71 
Paris  Exposition  -  -  70,  84,  85,  129 
Paris  International  Electrical 

Congress         -         -     207,  208,  215 
Parliamentary  reports  -  -       91 

Parliament,  Burning  of  Houses  of, 

1834       ....  35 

Parliamentary  standard        -         -     249 

Parthenon 25 

Par  value 167 

Passus 26 

Paucton        -         -  7,  10,  37 

Pavilion  Breteuil  77 

Pence    -  -       32 

Pendulum  as  a  unit  of  length 

15,  37,  42,  44,  46,  48,  49,  111,  245 
Penny,  or  sterling  -  -  -  32 
Pennyweight  -  -  -  -  32 


PAGE 

Perch 45 

Perche 97 

Perpignan,  Base  at  -  -  -  55 
Pertica  or  Decempeda  26 

Peru,  Toise  de      -  44,  249 

Petrie,  Flinders    -         -         -  18,  23,  24 

Pfund 82,  83,  86 

Philippine  Tariff  Act,  1901  -  132 

Philosophical  drachm,  ounce,  and 

pound    -  ...       98 

Phoenician  weights  and  measures  18,  21 
Physicalisch  Technische  Reich  san 

stalt       ....  152 

Picard 43 

Pied  de  roi   -        -  -  37 

Pied  geometrique          -  44 

Pied  (Swiss)          ...  97 

Pile  of  Charlemagne  -  -  39,  250 
Pinte  (French)  -  -  -  -  145 
Platinum  for  standards  -  236,  257 
Platinum  Iridium  standards 

74,  77,  148,  221,  252 
Platinum  metres  -         -  62,  251 

Pliny    ....  -      26 

Plumb-line  -  "  -  -  -  -  15 
Plutarch  -  -  -  25 

Pluviose        ...  -       53 

Polar  axis 164 

Polar  flattening    -         -         -  48,  59,  62 

Polaris 39 

Polar  radius          -        -         -         -     164 

Polybius 26 

Polychrome  Bible  -  -  -  14 
Porto  Rico,  Metric  measures  in  -  132 
Portugal,  Metric  system  in  -  -  94 
Postal  Congress  of  1863  -  -  126 
Pot  (Swiss)  ---  -  97 

Potential  difference,  Unit  of  -  203 
Pound  -  27,  32,  33,  34,  38,  119,  248 
Power,  Unit  of  -  -  -  -  202 
Pratt  &  Whitney  Co.  -  -  -  185 

Prairial 53 

Prescriptions,  Metric  -  -  -  197 
Priestley,  Dr.  -  -  -  98 

Prony  -  -       54 

Ptolemy  Lagos  24 

Pyx  chapel  -  30 

Quadrant  (unit  of  inductance)  -  208 
Quantity  of  electricity,  Unit  203,  209 

Quarteron 39 

Quarteron  (Swiss  unit  of  capacity)  97 
Queen  Anne,  Gallon  of  -  -  35 
Queen  Elizabeth,  Standards  of 

35,  36,  243,  247 

Quintal  ....  146,  147 
Quito,  arc  ....  44 


Railway  shares 


167 


302 


INDEX 


Rawlinson    - 
Rayleigh,  Lord     - 
Rayon  astronomique 
Reed     - 
Regnault 
Reichsanstalt 
Resistance    - 


PAGE 

-  13 

-  207 

-  43 

-  15 

-  69 
152,  241 

203,  204,  205 


Retail  Trades  Associations  favour 

metric  system        -         -         -     102 
Rhine  countries,  Measures  in        -       26 

Rhine  foot 40 

Richard  I. ,  Laws  of      -         -  31 

Riders 148 

Ridge  way  -  -  -  -  3,  4,  18 
Rock  crystal  standards  -  148,  236 
Rogers,  Wm.  A.  -  -  -  185,  235 
Rome,  Weights  and  measures  of  -  26 
Rosenberger  -  -  -  204,  205 
Rosebery,  Lord  -  -  -  -  101 
Rowland,  Henry  A.  -  207,  211,  226 
Royal  foot  (French)  -  -  37 

Royal  Society  (British) 

46,  47,  84,  99,  101 

Ruggles,  Samuel  B.  -  -  -  126 
Ruprecht  balance  -  -  -  237 
Russia,  Weights  and  measures  of  94 
Ruthe 82 

Salces,  Base  at  -         -         -       55 

Sagene-  -  -  ...  94 
Sar  -  -  -  •  -  -  15 

Sauvage,  Ed.  -  -  -  -  183 
Saxon  weights  and  measures  30,  31,  32 

Schoenus 23 

Schools,  Metric  system  in  125,  129,  165 
Schiraz,  Anania  de  -  25 

Schumacher,  Professor  -  -  248 
Screws,  Cutting  of  182 

Screw-cutting  lathe  -  -  -  186 
Screw  threads  182,  183,  184,  185,  186 

Seah 21 

Second's  pendulum      15,  36,  37,  44,  46, 
48,  49,  111,  245 

Sellers,  Dr.  Coleman  -  -  -  161 
Sellers,  Wm.  -  -  -  -  183 
Seller's  standard  -  183 

Seller's  thread  -  -  -  -  185 
Senkereh  tablet  -  13,  17 

Sensibility  of  balance  -  -  -  239 
Sexagesimal  system  12 

Sextarii 28 

Shaku 93 

Shaw-Caldecott,  W.     -         -         13,  17 

She 15 

Sheet  and  plate  iron  and   steel, 

U.S.  standard  scale        -  131 

Shekel,  Babylonian  16 

Shekels  of  the  Hebrews  -  -  21 
Shilling 32 


PAGE 

Shoppen 83 

Short  ton 168 

Shuckburgh,  Sir  George 

120,  230,  231,  245 

Shuckburgh  scale  -         -         -     100 

Shuckburgh's  comparator  -  230,  231 
Siemens,  Alex.  -  -  186,  216,  217 
Siemens,  Werner  -  205 

Silver  coinage  by  metric  weight  -  128 
Silver  voltameter  -  210,211,212 
Sizes  of  screw  threads  -  -  -  184 

Skaal-Pund 96 

Smith,  Prof.  R.  H.  -  -  -  135 
Smyth,  Piazzi  -  -  -  -  10 
Societe  d'Encouragement  pour 

1'Industrie  Nationale      -         -     183 
Solid  angle  unit    -         -         -         -     202 

Solive 65 

Solon    -         -        -   '     -        -        -       27 

Sols 38,  39 

Solvay  Process  Company  -  -  168 
South  America,  Metric  system 

used  in  -  -     160 

South  and  Central  America,  Metric 

system  employed  in     103,  107,  108 
Spain,  Adoption  of  metric  system 

in  -  -       95 

Span     -  6 

Spanish  Geographical  and  Statis- 
tical Institute  -         -     158 
Spartan    States    use    Babylonian 

talent 27 

Specific  gravity  of  standards  -  238 
Specific  gravity  tables  -  -  290,  291 
Specifications  for  ampere  and  volt  211 
Spencer  -  -  -  -  102 

Square  measures  -  142 

Stadion 25 

Standard  avoirdupois  pound          -     248 
Standard  bars  for  base  measure- 
ments      141 

Standard  kilogram  and  meter  -  254 
Standard  cell  212,  213,  214,  215,  216 
Standard  gauges  -  176 

Standardization    -         -         -  154 

Standards  of  capacity  -  -  -  240 
Standard  sizes  :  -  175 

Standard  troy  pound  of  1758  -  34 
Standard  troy  pound,  U.S.  Mint  119 
Standard  yard  (Elizabeth)  -  36,  243 
Standard  yard  (Henry  VII. )  3(5,  243 
Standard  yard,  British 

244,  245,  246,  247 

Standard  yards  of  United  States  114,247 
Standards  and  comparison  -  -  218 
Standards  Commission,  British  35,  100 
Standards  office  -  246 

Standards  of  mass          -  -     286 

Standards  of  the  Netherlands       -       i)3 


INDEX 


308 


PAOK 

Standards  of  the  United  States  -  122 
Standards  of  resistance  -  -  241 
Standards  of  resistance,  current 

and  electrical  pressure  -  -  242 
Standards,  Permanence  of  -  -  228 
State  standards  -  -  -  121,  122 

Steel  tape 140 

Stere  -  -  -  -  54,  144 

Sternberg,  Gen.  Geo.  M.  -  -  196 
Strabo  -  -  23,  26 

St.  Louis  Exposition  -  -  -  216 
St.  Petersburg  Academy  of 

Sciences  71 

Sweden,  Metric  system  adopted  -  95 
Switzerland,  Metric  system  in  82,  97 
Syrian  standard  21 

Systeme  International,  S.I.  or 

S.J. 183 

Table-spoonful  -  -  -  -  198 
Talent,  Alexandrian  25 

Talleyrand 46 

Taps  and  dies  ....  183 
Teachers'  Associations  endorse 

metric  system         -         -         -     102 

Teaspoonful 198 

Tel-el-Amarna  correspondence  -  19 
Temperature  measurements  -  -  227 

Thermidor 53 

Thermometers,  thermometric  meas- 
urements       -  227 
Thermometer  scales,  Table  of       -     290 

Tillet 47 

Tittman,  0.  H.     -         -         -         -     120 

Toise 38,  44,  97 

Toise  de  ma9ons  38 

Toise  de  Perou  -  -  38,  54,  249 
Toise  du  Grand  Chatelet  -  38,  249 
Torque,  Unit  of  -  -  -  -  202 
Tortuosity,  Unit  of  -  -  202 

Totten,  C.  A.  S.  -  -  -  -  10 
Tours,  Standards  of  -  -  -  39 
Tower  Pound  -  -  -  32,  33,  34 
Tralles-  -  -  -  62,  81,  82,  114 
Transits  -  -  -  58 

Treasury  Department,  U.S.,  Stan- 
dards of          -         -         -         -     123 
Treaty,  Metric      ....       75 
Tresca  -  74,  252,  253,  254,  255 

Trigonometrical  survey         -         -       55 

Trough  ton 230 

Troughton  scale  -  114,  121,  122,  247 
Troy  pound  -  -  25,  33,  34,  119,  248 
Troyes,  Standards  of  -  -  33,  39 
Trowbridge,  John  -  -  -  211 
Tumblerful  -  198 

Tungri,  Belgic  foot  of  -  -  -  31 
Turkey,  Measures  of  -  97 

Tweedmouth         ....     102   I 


PAGE 

Ulna 26 

Ulna  or  Aulne  ...  -  31 
Unit  acceleration  -  -  -  200 
United  States,  Weights  and  meas- 
ures of  -  -  -  103,  109 
United  States  Army,  Med.  Dept.  195 
United  States  Bureau  of  Standards  131 
United  States  Navy,  Med.  Dept.  195 
United  States  Pharmacopoeia  -  192 
Unit  of  Intensity  of  Magnetism  -  200 

Units 1 

Unit  velocity        -         -         -         -  200 

Units,  Absolute                               -  200 

Units,  Arbitrary           -         -         -  5 

Units,  Fundamental     -         -         -  8 

Units,  Natural      ....  5 

Upton,  J.  K.         -         -         -         -  91 

Ush 15 

Usuelle         -        -        -        -  65,  66,  67 


Vauclain,  S.  M.    - 
Vandermonde 
Van  Swinden 
Vendemiaire 
Vernet,  Base  near 
Vienna  coin  treaty 
Virga  or  Verge 
Virga    - 

Virgula  geometrica 
Volt     -         --. 
Volume,  Measures  of    - 
Von  Humboldt,  Alex.  - 


-  188 

-  54 
-  61,  80,  82, 

-  53 

-  55 

-  85 

-  31 
.   43 

-  43 
206,  209,  212 

-  143 

-  200 


Wales,  Philip  S.  -  -  -  -  195 
Warren,  Gen.  Charles  10 

Washburne,  E.  B.  -  -  -  130 
Washington,  President  111,  113 

Watchmakers  use  of  metric  threads   181 

Water  clock 12 

Watt  (unit)  -  -  202,  206,  208,  209 
Watt,  James  ....  98 
Wave  length  of  light  -  229,  260,  261, 
262,  263,  264,  265,  266 
Weber,  Wilhelm  -  -  201,204,205 
Weighing,  Earliest  -  -  -  4 
Weights  and  Measures  Act 

(British,  1878)        -         -         -     101 
Westminster  Abbey     -         -         -       30 

Westoncell 216 

Wheat  bushels  -  -  -  '  -  156 
Whitworth  standard  -  -  183,  186 
Willans  &  Robinson,  Messrs.  187 

William  the  Conqueror,  Decree  of  30 
Williams,  R.  P.  -  -  -  125 

Winchester  standards  -  -  -  30 
Winchester  bushel  -  -  35,  122 
Winchester  corn  gallon  -  -  35 
Wine  gallon  -  -  -  -  35 


304 


INDEX 


Wineglass   - 

Windom,  Secretary  of  the  Treasury   159 

Wire  and  sheet  metals 

Wolf,  C.        - 

Wolf,  M.      - 

Wolff,  F.  A. 

Wollaston,  Wm.  H.      - 

Wood  worth,  John  M.  - 

Work,  Unit  of      - 

World's  Columbian  Exposition 


PAGE 

-     198 

PAGE 
Wrottesley,  Sir  John   ...       99 

mry   159 

-     176 

Yard  or  gird                                    30,  31 

230,  251 

Yard  standards    -         36,  1  14,  243,  247 

-    230 

Yates,  James        ....       84 

206,  215 

Young,  Dr.  Thomas                              99 

-       99 

Yusdrumin  pound  of  Charlemagne      29 

-     195 

202,  206 

Zollpfund     -         -         -         -         86,  89 

-    208 

Zollverein     -        •        -        -         -       86 

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